无码日韩精品一区二区免费暖暖,久久精品国产精品亚洲,开心播播网,女人床技48动态图,国产精品无码免费专区午夜

一、摘要

為(wei)支撐可再(zai)生能(neng)源(yuan)大比例接入新型電(dian)力系(xi)(xi)(xi)統(tong)(tong)(tong)，大幅(fu)提(ti)升(sheng)燃(ran)煤機(ji)(ji)組靈(ling)活(huo)性，該文提(ti)出耦合燃(ran)煤機(ji)(ji)組的(de)熔(rong)(rong)(rong)(rong)鹽(yan)(yan)(yan)(yan)儲(chu)(chu)能(neng)系(xi)(xi)(xi)統(tong)(tong)(tong)并(bing)進行(xing)熔(rong)(rong)(rong)(rong)鹽(yan)(yan)(yan)(yan)工質篩選。針對(dui)350MW靈(ling)活(huo)燃(ran)煤機(ji)(ji)組，熔(rong)(rong)(rong)(rong)鹽(yan)(yan)(yan)(yan)儲(chu)(chu)能(neng)系(xi)(xi)(xi)統(tong)(tong)(tong)承擔3%Pe/min升(sheng)負(fu)荷速(su)率(lv)目標(biao)下(xia)，綜合汽(qi)(qi)輪機(ji)(ji)熱力與關鍵設(she)備傳熱分(fen)析(xi)，從熔(rong)(rong)(rong)(rong)鹽(yan)(yan)(yan)(yan)基本(ben)(ben)物性出發，重點研究(jiu)了二元(yuan)(yuan)鹽(yan)(yan)(yan)(yan)(60%NaNO3+40%KNO3)和三(san)元(yuan)(yuan)鹽(yan)(yan)(yan)(yan)(53%KNO3+40%NaNO2+7%NaNO3)對(dui)熔(rong)(rong)(rong)(rong)鹽(yan)(yan)(yan)(yan)蒸(zheng)汽(qi)(qi)發生系(xi)(xi)(xi)統(tong)(tong)(tong)發電(dian)效(xiao)率(lv)、系(xi)(xi)(xi)統(tong)(tong)(tong)復雜性及(ji)投(tou)資成(cheng)本(ben)(ben)的(de)影響(xiang)。發現二元(yuan)(yuan)鹽(yan)(yan)(yan)(yan)分(fen)解(jie)(jie)溫(wen)度高(gao)，可產(chan)生較高(gao)品位(wei)蒸(zheng)汽(qi)(qi)，熔(rong)(rong)(rong)(rong)鹽(yan)(yan)(yan)(yan)蒸(zheng)汽(qi)(qi)發生系(xi)(xi)(xi)統(tong)(tong)(tong)的(de)平均(jun)(jun)發電(dian)效(xiao)率(lv)為(wei)36.7%，三(san)元(yuan)(yuan)鹽(yan)(yan)(yan)(yan)因(yin)分(fen)解(jie)(jie)溫(wen)度低，平均(jun)(jun)發電(dian)效(xiao)率(lv)僅為(wei)29.2%。與三(san)元(yuan)(yuan)鹽(yan)(yan)(yan)(yan)相比，二元(yuan)(yuan)鹽(yan)(yan)(yan)(yan)熔(rong)(rong)(rong)(rong)點高(gao)，熔(rong)(rong)(rong)(rong)鹽(yan)(yan)(yan)(yan)蒸(zheng)汽(qi)(qi)發生系(xi)(xi)(xi)統(tong)(tong)(tong)需從汽(qi)(qi)輪機(ji)(ji)抽汽(qi)(qi)預熱熔(rong)(rong)(rong)(rong)鹽(yan)(yan)(yan)(yan)系(xi)(xi)(xi)統(tong)(tong)(tong)給水，以(yi)防止熔(rong)(rong)(rong)(rong)鹽(yan)(yan)(yan)(yan)凝固堵塞，增加了系(xi)(xi)(xi)統(tong)(tong)(tong)復雜。采(cai)用二元(yuan)(yuan)鹽(yan)(yan)(yan)(yan)，熔(rong)(rong)(rong)(rong)鹽(yan)(yan)(yan)(yan)蒸(zheng)汽(qi)(qi)發生系(xi)(xi)(xi)統(tong)(tong)(tong)運行(xing)溫(wen)度高(gao)，在相同升(sheng)負(fu)荷需求(qiu)下(xia)，熔(rong)(rong)(rong)(rong)鹽(yan)(yan)(yan)(yan)流量、用量、儲(chu)(chu)罐(guan)及(ji)換熱器體積均(jun)(jun)減小，投(tou)資成(cheng)本(ben)(ben)比三(san)元(yuan)(yuan)鹽(yan)(yan)(yan)(yan)系(xi)(xi)(xi)統(tong)(tong)(tong)降(jiang)低1000萬元(yuan)(yuan)。基于本(ben)(ben)文研究(jiu)，建議(yi)采(cai)用二元(yuan)(yuan)鹽(yan)(yan)(yan)(yan)儲(chu)(chu)能(neng)系(xi)(xi)(xi)統(tong)(tong)(tong)，以(yi)實現熔(rong)(rong)(rong)(rong)鹽(yan)(yan)(yan)(yan)系(xi)(xi)(xi)統(tong)(tong)(tong)高(gao)效(xiao)性及(ji)安(an)全(quan)性，支撐超靈(ling)活(huo)燃(ran)煤發電(dian)。

二、引言

為(wei)支撐2030年(nian)碳(tan)達峰(feng)和(he)(he)2060年(nian)碳(tan)中和(he)(he)的(de)(de)“雙碳(tan)”目標，我國(guo)(guo)(guo)未來(lai)能(neng)(neng)源消費增量(liang)主要(yao)來(lai)自(zi)于清潔能(neng)(neng)源，大幅減少化(hua)石能(neng)(neng)源利(li)用(yong)成為(wei)不(bu)可(ke)(ke)(ke)逆(ni)轉的(de)(de)趨(qu)勢。太陽能(neng)(neng)、風能(neng)(neng)等(deng)(deng)可(ke)(ke)(ke)再(zai)生能(neng)(neng)源具有間(jian)歇性(xing)、波動性(xing)，隨著(zhu)大規(gui)模新(xin)能(neng)(neng)源發(fa)電(dian)(dian)(dian)裝機(ji)持續接(jie)入電(dian)(dian)(dian)網，部分(fen)地(di)區(qu)新(xin)能(neng)(neng)源消納壓力(li)凸顯，造(zao)成棄(qi)風棄(qi)光局面。為(wei)提升電(dian)(dian)(dian)力(li)系統(tong)(tong)穩(wen)定(ding)性(xing)，高比例新(xin)能(neng)(neng)源電(dian)(dian)(dian)力(li)系統(tong)(tong)亟(ji)需與之匹(pi)配的(de)(de)靈活(huo)(huo)可(ke)(ke)(ke)調(diao)度資(zi)(zi)(zi)源。目前電(dian)(dian)(dian)力(li)系統(tong)(tong)的(de)(de)靈活(huo)(huo)可(ke)(ke)(ke)調(diao)度資(zi)(zi)(zi)源主要(yao)包括燃氣(qi)輪機(ji)、抽水(shui)蓄能(neng)(neng)與靈活(huo)(huo)煤(mei)(mei)電(dian)(dian)(dian)機(ji)組(zu)等(deng)(deng)。由(you)于我國(guo)(guo)(guo)“富(fu)煤(mei)(mei)、貧(pin)油、缺氣(qi)”的(de)(de)自(zi)然資(zi)(zi)(zi)源稟賦，燃氣(qi)輪機(ji)不(bu)適合在我國(guo)(guo)(guo)大面積(ji)推廣(guang)；抽水(shui)蓄能(neng)(neng)建設周期(qi)長，建設成本較高，且對建造(zao)場地(di)要(yao)求較為(wei)苛刻(ke)，難以短時間(jian)內成為(wei)我國(guo)(guo)(guo)能(neng)(neng)夠(gou)提供大量(liang)靈活(huo)(huo)性(xing)的(de)(de)發(fa)電(dian)(dian)(dian)形式。2023年(nian)煤(mei)(mei)電(dian)(dian)(dian)機(ji)組(zu)保持安(an)全(quan)(quan)(quan)高效(xiao)運行，全(quan)(quan)(quan)年(nian)累計發(fa)電(dian)(dian)(dian)5.35萬億千(qian)瓦(wa)時，以占全(quan)(quan)(quan)國(guo)(guo)(guo)52%的(de)(de)裝機(ji)規(gui)模貢(gong)獻了(le)占全(quan)(quan)(quan)國(guo)(guo)(guo)63%的(de)(de)發(fa)電(dian)(dian)(dian)量(liang)，電(dian)(dian)(dian)網調(diao)峰(feng)仍需要(yao)燃煤(mei)(mei)機(ji)組(zu)發(fa)揮(hui)兜(dou)底保供作用(yong)。近期(qi)煤(mei)(mei)電(dian)(dian)(dian)不(bu)可(ke)(ke)(ke)能(neng)(neng)大規(gui)模退役，而是逐步(bu)由(you)提供電(dian)(dian)(dian)力(li)的(de)(de)主體電(dian)(dian)(dian)源轉變為(wei)支撐性(xing)和(he)(he)調(diao)節(jie)性(xing)電(dian)(dian)(dian)源。因此，煤(mei)(mei)電(dian)(dian)(dian)是經濟可(ke)(ke)(ke)行、安(an)全(quan)(quan)(quan)可(ke)(ke)(ke)靠的(de)(de)靈活(huo)(huo)調(diao)節(jie)資(zi)(zi)(zi)源，燃煤(mei)(mei)機(ji)組(zu)的(de)(de)靈活(huo)(huo)性(xing)改造(zao)已為(wei)新(xin)能(neng)(neng)源消納發(fa)揮(hui)了(le)重要(yao)作用(yong)。

燃(ran)(ran)(ran)煤機組(zu)(zu)(zu)(zu)的(de)靈(ling)(ling)活(huo)性通(tong)常是(shi)(shi)指(zhi)運行靈(ling)(ling)活(huo)性，即能適應(ying)機組(zu)(zu)(zu)(zu)出力(li)(li)大幅波(bo)動、快(kuai)速響應(ying)各類變(bian)(bian)化(hua)的(de)能力(li)(li)，包括(kuo)調(diao)峰(feng)(feng)負(fu)(fu)荷(he)(he)(he)(he)范圍、爬坡(po)速率(lv)和(he)(he)啟停(ting)時間等。靈(ling)(ling)活(huo)性改(gai)造后(hou)的(de)燃(ran)(ran)(ran)煤機組(zu)(zu)(zu)(zu)最(zui)低(di)負(fu)(fu)荷(he)(he)(he)(he)達(da)(da)(da)到(dao)25%~40%Pe，受限于設備安全及可靠性，燃(ran)(ran)(ran)煤機組(zu)(zu)(zu)(zu)難以實現日啟停(ting)調(diao)峰(feng)(feng)。利用(yong)燃(ran)(ran)(ran)煤機組(zu)(zu)(zu)(zu)參與電網調(diao)峰(feng)(feng)的(de)代表性國(guo)家(jia)，德國(guo)和(he)(he)丹麥(mai)已取得很好的(de)成果(guo)，德國(guo)燃(ran)(ran)(ran)煤機組(zu)(zu)(zu)(zu)改(gai)造集中于深度調(diao)峰(feng)(feng)和(he)(he)快(kuai)速啟停(ting)能力(li)(li)，變(bian)(bian)負(fu)(fu)荷(he)(he)(he)(he)速率(lv)達(da)(da)(da)到(dao)4%~6%Pe/min。丹麥(mai)以熱(re)電聯產(chan)機組(zu)(zu)(zu)(zu)為主(zhu)，輔以熱(re)電解耦、儲能技(ji)術(shu)(shu)以及生(sheng)物質(zhi)摻燒(shao)等，變(bian)(bian)負(fu)(fu)荷(he)(he)(he)(he)速率(lv)可達(da)(da)(da)到(dao)5%Pe/min。此(ci)(ci)外(wai)，歐美發(fa)達(da)(da)(da)國(guo)家(jia)燃(ran)(ran)(ran)氣(qi)資(zi)源(yuan)相對(dui)豐富，電網調(diao)峰(feng)(feng)主(zhu)要(yao)(yao)依靠燃(ran)(ran)(ran)氣(qi)電站。燃(ran)(ran)(ran)氣(qi)機組(zu)(zu)(zu)(zu)本質(zhi)靈(ling)(ling)活(huo)、變(bian)(bian)負(fu)(fu)荷(he)(he)(he)(he)速率(lv)可達(da)(da)(da)5%Pe/min。為解決(jue)可再(zai)生(sheng)能源(yuan)分鐘(zhong)級(ji)波(bo)動發(fa)電并(bing)網帶來的(de)挑戰(zhan)(如圖(tu)1所(suo)示(shi))，對(dui)標國(guo)外(wai)調(diao)峰(feng)(feng)機組(zu)(zu)(zu)(zu)的(de)變(bian)(bian)負(fu)(fu)荷(he)(he)(he)(he)速率(lv)，作(zuo)者(zhe)所(suo)在團隊(dui)聯合多家(jia)企業(ye)共同申(shen)請了能源(yuan)領域首臺(套)。該(gai)首臺套主(zhu)要(yao)(yao)針對(dui)350MW燃(ran)(ran)(ran)煤機組(zu)(zu)(zu)(zu)其高負(fu)(fu)荷(he)(he)(he)(he)段(50%~100%THA)具有6%Pe/min的(de)升(sheng)負(fu)(fu)荷(he)(he)(he)(he)速率(lv)是(shi)(shi)重要(yao)(yao)指(zhi)標之(zhi)一。鍋爐(lu)是(shi)(shi)制約傳統燃(ran)(ran)(ran)煤發(fa)電機組(zu)(zu)(zu)(zu)變(bian)(bian)負(fu)(fu)荷(he)(he)(he)(he)速率(lv)的(de)關(guan)鍵之(zhi)一，制約因素包括(kuo)：快(kuai)速變(bian)(bian)負(fu)(fu)荷(he)(he)(he)(he)時，工質(zhi)溫壓參數快(kuai)速變(bian)(bian)化(hua)導(dao)(dao)致厚壁元件(jian)產(chan)生(sheng)較大熱(re)應(ying)力(li)(li)，影響設備壽命；鍋爐(lu)給粉系(xi)統響應(ying)跟不(bu)上變(bian)(bian)負(fu)(fu)荷(he)(he)(he)(he)速率(lv)要(yao)(yao)求，導(dao)(dao)致機組(zu)(zu)(zu)(zu)響應(ying)整體滯后(hou)；鍋爐(lu)干濕態轉換導(dao)(dao)致的(de)水(shui)動力(li)(li)不(bu)穩定性加劇，對(dui)機組(zu)(zu)(zu)(zu)運行安全提(ti)出挑戰(zhan)。為此(ci)(ci)，作(zuo)者(zhe)所(suo)在團隊(dui)擬研發(fa)柔(rou)性水(shui)冷壁、創新集箱管道連接形式(shi)等鍋爐(lu)關(guan)鍵技(ji)術(shu)(shu)，可使鍋爐(lu)升(sheng)負(fu)(fu)荷(he)(he)(he)(he)速率(lv)提(ti)升(sheng)到(dao)3%Pe/min(如圖(tu)1所(suo)示(shi))，但離(li)6%Pe/min的(de)目標仍然有較大差距。

近年來，在(zai)(zai)國(guo)內企業及科研(yan)(yan)院所(suo)的共(gong)同(tong)努(nu)力下(xia)，我(wo)國(guo)太陽(yang)能(neng)(neng)熔(rong)(rong)鹽(yan)(yan)(yan)儲(chu)(chu)熱(re)(re)發(fa)電技術(shu)逐(zhu)步成(cheng)熟并達到(dao)世界先進水平，相繼(ji)建成(cheng)了多個耦(ou)合熔(rong)(rong)鹽(yan)(yan)(yan)儲(chu)(chu)熱(re)(re)光熱(re)(re)電站(zhan)。在(zai)(zai)太陽(yang)能(neng)(neng)熔(rong)(rong)鹽(yan)(yan)(yan)儲(chu)(chu)熱(re)(re)發(fa)電技術(shu)基礎上(shang)，國(guo)內開始研(yan)(yan)發(fa)耦(ou)合熔(rong)(rong)鹽(yan)(yan)(yan)儲(chu)(chu)熱(re)(re)的靈活燃煤發(fa)電技術(shu)，并取(qu)得了較大進展。因此，在(zai)(zai)傳統(tong)燃煤機(ji)組上(shang)增加(jia)熔(rong)(rong)鹽(yan)(yan)(yan)系(xi)統(tong)是(shi)彌補鍋(guo)爐升(sheng)(sheng)負荷速率(lv)不足(zu)的新思路(如圖(tu)1所(suo)示)，即熔(rong)(rong)鹽(yan)(yan)(yan)系(xi)統(tong)通過(guo)熔(rong)(rong)鹽(yan)(yan)(yan)存儲(chu)(chu)鍋(guo)爐部分(fen)熱(re)(re)量，在(zai)(zai)機(ji)組需要快速升(sheng)(sheng)負荷時釋放(fang)，通過(guo)熔(rong)(rong)鹽(yan)(yan)(yan)系(xi)統(tong)儲(chu)(chu)放(fang)熱(re)(re)完成(cheng)機(ji)組能(neng)(neng)量時空調控。高負荷放(fang)熱(re)(re)階段，熔(rong)(rong)鹽(yan)(yan)(yan)加(jia)熱(re)(re)給(gei)水產(chan)生蒸汽，與鍋(guo)爐產(chan)生的蒸汽共(gong)同(tong)匯入(ru)汽輪機(ji)做功，熔(rong)(rong)鹽(yan)(yan)(yan)系(xi)統(tong)和(he)鍋(guo)爐分(fen)別貢獻3%Pe/min的升(sheng)(sheng)負荷速率(lv)，機(ji)組達到(dao)6%Pe/min的升(sheng)(sheng)負荷速率(lv)(如圖(tu)1所(suo)示)。

為(wei)確定合理的(de)(de)升(sheng)負(fu)荷(he)(he)(he)區間，懷柔(rou)實驗室(shi)對潤(run)港電(dian)廠(chang)(chang)#1、2機(ji)(ji)，宏業電(dian)廠(chang)(chang)#1、2機(ji)(ji)，撫寧電(dian)廠(chang)(chang)#1、2機(ji)(ji)6臺調(diao)節(jie)性火電(dian)機(ji)(ji)組(zu)(zu)進行調(diao)研(yan)，對五個(ge)典型周1萬多(duo)組(zu)(zu)AGC數(shu)據進行分析(xi)，發現(xian)：機(ji)(ji)組(zu)(zu)在50%Pe及以(yi)(yi)上(shang)進行升(sheng)負(fu)荷(he)(he)(he)的(de)(de)概率(lv)(lv)(lv)為(wei)74%，升(sheng)負(fu)荷(he)(he)(he)跨(kua)度10%~25%Pe的(de)(de)占比最高。因此，綜合考慮熔鹽蒸汽發生(sheng)系統(tong)(tong)設備成本(ben)、運行經(jing)濟性、液位和壓力控制、產汽參數(shu)波動范圍及匯汽量對汽輪機(ji)(ji)的(de)(de)影響。將(jiang)熔鹽系統(tong)(tong)支(zhi)撐燃(ran)煤機(ji)(ji)組(zu)(zu)升(sheng)負(fu)荷(he)(he)(he)的(de)(de)區間定為(wei)X→X+25%THA(50%THA≤X≤75%THA)。以(yi)(yi)75%THA-100%THA升(sheng)負(fu)荷(he)(he)(he)范圍為(wei)例，如圖2所(suo)示，為(wei)實現(xian)機(ji)(ji)組(zu)(zu)6%Pe/min的(de)(de)升(sheng)負(fu)荷(he)(he)(he)速率(lv)(lv)(lv)，鍋爐按3%Pe/min速率(lv)(lv)(lv)線性增加(jia)到機(ji)(ji)組(zu)(zu)目標(biao)負(fu)荷(he)(he)(he)，熔鹽蒸汽發生(sheng)系統(tong)(tong)以(yi)(yi)3%Pe/min速率(lv)(lv)(lv)升(sheng)到峰值后逐(zhu)漸降低(di)負(fu)荷(he)(he)(he)退出。

常見的熔(rong)鹽(yan)(yan)由堿(jian)金屬、碳酸鹽(yan)(yan)、硝(xiao)酸鹽(yan)(yan)以及磷(lin)酸鹽(yan)(yan)等組成。熔(rong)鹽(yan)(yan)在傳熱(re)、儲熱(re)、熱(re)處理、高(gao)溫電化(hua)學(xue)電鍍(du)和(he)材料加工等領域得到廣泛(fan)應(ying)(ying)用(yong)，也(ye)作為液態燃料和(he)儲熱(re)介(jie)質應(ying)(ying)用(yong)于(yu)飛機(ji)/熔(rong)鹽(yan)(yan)反應(ying)(ying)堆實驗和(he)核反應(ying)(ying)堆。熔(rong)鹽(yan)(yan)具有熱(re)容量大(da)、蒸汽壓低(di)、導電性(xing)好、熱(re)穩(wen)定性(xing)和(he)化(hua)學(xue)穩(wen)定性(xing)等諸多優勢，是公認(ren)的中高(gao)溫傳熱(re)蓄熱(re)介(jie)質。

熔(rong)(rong)鹽(yan)(yan)(yan)(yan)應用(yong)于實際工程需要(yao)(yao)防止凝固和(he)(he)分解，因此常關注熔(rong)(rong)點(dian)(dian)和(he)(he)沸點(dian)(dian)，兩個(ge)參數決定了(le)熔(rong)(rong)鹽(yan)(yan)(yan)(yan)運(yun)行溫度，限(xian)制了(le)不同熔(rong)(rong)鹽(yan)(yan)(yan)(yan)的應用(yong)領域。熔(rong)(rong)鹽(yan)(yan)(yan)(yan)按(an)熔(rong)(rong)點(dian)(dian)從大到(dao)小(xiao)可分為(wei)(wei)(wei)氟(fu)化(hua)(hua)鹽(yan)(yan)(yan)(yan)、碳酸(suan)鹽(yan)(yan)(yan)(yan)、氯(lv)化(hua)(hua)鹽(yan)(yan)(yan)(yan)、硝酸(suan)鹽(yan)(yan)(yan)(yan)。其中，高(gao)熔(rong)(rong)點(dian)(dian)氟(fu)化(hua)(hua)鹽(yan)(yan)(yan)(yan)作為(wei)(wei)(wei)冷卻劑，用(yong)于釷基堆核能系統(tong)研(yan)發；熔(rong)(rong)融碳酸(suan)鹽(yan)(yan)(yan)(yan)作為(wei)(wei)(wei)電(dian)解質，用(yong)于新型燃料電(dian)池(chi)研(yan)發，氯(lv)化(hua)(hua)鹽(yan)(yan)(yan)(yan)和(he)(he)硝酸(suan)鹽(yan)(yan)(yan)(yan)運(yun)行溫度符合太陽(yang)能儲熱(re)電(dian)站需求(qiu)，但(dan)氯(lv)化(hua)(hua)鹽(yan)(yan)(yan)(yan)腐蝕性強(qiang)，因此商(shang)業(ye)化(hua)(hua)太陽(yang)能儲熱(re)電(dian)站常采用(yong)二(er)元鹽(yan)(yan)(yan)(yan)(Solar Salt)和(he)(he)三(san)元鹽(yan)(yan)(yan)(yan)（Hitec Salt）。耦合燃煤發電(dian)的熔(rong)(rong)鹽(yan)(yan)(yan)(yan)儲熱(re)，對熔(rong)(rong)鹽(yan)(yan)(yan)(yan)運(yun)行溫度區間要(yao)(yao)求(qiu)與(yu)太陽(yang)能儲熱(re)電(dian)站相近。因此，本文研(yan)究過程中考慮采用(yong)二(er)元鹽(yan)(yan)(yan)(yan)和(he)(he)三(san)元鹽(yan)(yan)(yan)(yan)。

本(ben)文針對(dui)耦合350 MW燃煤(mei)發(fa)(fa)電機組的(de)熔鹽(yan)(yan)(yan)系(xi)統展(zhan)開研(yan)究(jiu)，熔鹽(yan)(yan)(yan)系(xi)統直接吸收鍋爐多余熱(re)量進行(xing)(xing)儲熱(re)，在機組高(gao)負(fu)荷(he)段(50%-100%THA)，熔鹽(yan)(yan)(yan)加(jia)熱(re)給水產生(sheng)(sheng)(sheng)蒸汽匯(hui)入汽輪機，獨立承擔(dan)3%Pe/min的(de)升負(fu)荷(he)速率。不同種類熔鹽(yan)(yan)(yan)的(de)運(yun)行(xing)(xing)溫(wen)度、支撐升負(fu)荷(he)次(ci)數等決(jue)定(ding)了熔鹽(yan)(yan)(yan)蒸汽發(fa)(fa)生(sheng)(sheng)(sheng)系(xi)統的(de)發(fa)(fa)電效率、系(xi)統復(fu)雜性(xing)(xing)及投資成本(ben)。本(ben)文從熔鹽(yan)(yan)(yan)系(xi)統概念設計出(chu)發(fa)(fa)，綜(zong)合采用熱(re)力學、流動(dong)傳(chuan)熱(re)學等分析理論(lun)和方法，對(dui)二元(yuan)鹽(yan)(yan)(yan)和三元(yuan)鹽(yan)(yan)(yan)蒸汽發(fa)(fa)生(sheng)(sheng)(sheng)系(xi)統進行(xing)(xing)技術性(xing)(xing)和經濟性(xing)(xing)對(dui)比分析。研(yan)究(jiu)結果(guo)為未來耦合燃煤(mei)發(fa)(fa)電機組熔鹽(yan)(yan)(yan)系(xi)統的(de)設計提(ti)供(gong)支撐。

三、耦合燃煤發電的熔鹽系統

圖(tu)3為(wei)耦合(he)燃煤發(fa)(fa)電機(ji)組(zu)熔(rong)(rong)(rong)鹽(yan)(yan)(yan)(yan)系(xi)(xi)(xi)統(tong)(tong)(tong)(tong)的(de)(de)概念設(she)(she)計圖(tu)(紅線)，包括外掛式(shi)煙(yan)(yan)氣(qi)熔(rong)(rong)(rong)鹽(yan)(yan)(yan)(yan)儲(chu)熱(re)系(xi)(xi)(xi)統(tong)(tong)(tong)(tong)、熔(rong)(rong)(rong)鹽(yan)(yan)(yan)(yan)蒸汽(qi)(qi)(qi)(qi)發(fa)(fa)生(sheng)系(xi)(xi)(xi)統(tong)(tong)(tong)(tong)和(he)(he)熔(rong)(rong)(rong)鹽(yan)(yan)(yan)(yan)儲(chu)存系(xi)(xi)(xi)統(tong)(tong)(tong)(tong)三部分。熔(rong)(rong)(rong)鹽(yan)(yan)(yan)(yan)儲(chu)存系(xi)(xi)(xi)統(tong)(tong)(tong)(tong)是(shi)實(shi)現儲(chu)熱(re)和(he)(he)放(fang)(fang)熱(re)功(gong)(gong)能的(de)(de)連(lian)接紐帶，根據(ju)工藝要求設(she)(she)置了熱(re)鹽(yan)(yan)(yan)(yan)罐(guan)和(he)(he)冷鹽(yan)(yan)(yan)(yan)罐(guan)，分別(bie)存放(fang)(fang)高溫(wen)熔(rong)(rong)(rong)鹽(yan)(yan)(yan)(yan)和(he)(he)低(di)溫(wen)熔(rong)(rong)(rong)鹽(yan)(yan)(yan)(yan)。熔(rong)(rong)(rong)鹽(yan)(yan)(yan)(yan)系(xi)(xi)(xi)統(tong)(tong)(tong)(tong)通過(guo)(guo)高低(di)溫(wen)鹽(yan)(yan)(yan)(yan)罐(guan)將(jiang)外掛式(shi)煙(yan)(yan)氣(qi)熔(rong)(rong)(rong)鹽(yan)(yan)(yan)(yan)儲(chu)熱(re)系(xi)(xi)(xi)統(tong)(tong)(tong)(tong)與(yu)熔(rong)(rong)(rong)鹽(yan)(yan)(yan)(yan)蒸汽(qi)(qi)(qi)(qi)發(fa)(fa)生(sheng)系(xi)(xi)(xi)統(tong)(tong)(tong)(tong)耦合(he)，實(shi)現儲(chu)熱(re)、放(fang)(fang)熱(re)功(gong)(gong)能。外掛式(shi)煙(yan)(yan)氣(qi)熔(rong)(rong)(rong)鹽(yan)(yan)(yan)(yan)儲(chu)熱(re)系(xi)(xi)(xi)統(tong)(tong)(tong)(tong)為(wei)作者所(suo)在團隊原創技(ji)術，該系(xi)(xi)(xi)統(tong)(tong)(tong)(tong)設(she)(she)置獨立的(de)(de)引風機(ji)從(cong)鍋爐抽取合(he)適溫(wen)度的(de)(de)煙(yan)(yan)氣(qi)，送至煙(yan)(yan)氣(qi)熔(rong)(rong)(rong)鹽(yan)(yan)(yan)(yan)換(huan)熱(re)器(qi)加熱(re)熔(rong)(rong)(rong)鹽(yan)(yan)(yan)(yan)進行儲(chu)熱(re)，冷卻后的(de)(de)煙(yan)(yan)氣(qi)返回SCR入口(kou)(如圖(tu)3中的(de)(de)虛線回路)。儲(chu)熱(re)過(guo)(guo)程中需合(he)理抽取煙(yan)(yan)氣(qi)量，以保證鍋爐安全運行。當(dang)熔(rong)(rong)(rong)鹽(yan)(yan)(yan)(yan)系(xi)(xi)(xi)統(tong)(tong)(tong)(tong)接到(dao)輔助機(ji)組(zu)升(sheng)負荷(he)指令時，熔(rong)(rong)(rong)鹽(yan)(yan)(yan)(yan)蒸汽(qi)(qi)(qi)(qi)發(fa)(fa)生(sheng)系(xi)(xi)(xi)統(tong)(tong)(tong)(tong)開始運行。來(lai)自除(chu)氧(yang)器(qi)的(de)(de)給(gei)水經泵送后依次(ci)流經熔(rong)(rong)(rong)鹽(yan)(yan)(yan)(yan)汽(qi)(qi)(qi)(qi)水預熱(re)器(qi)、蒸發(fa)(fa)器(qi)和(he)(he)過(guo)(guo)熱(re)器(qi)，與(yu)來(lai)自熱(re)鹽(yan)(yan)(yan)(yan)罐(guan)的(de)(de)熔(rong)(rong)(rong)鹽(yan)(yan)(yan)(yan)逆流換(huan)熱(re)，產生(sheng)的(de)(de)過(guo)(guo)熱(re)蒸汽(qi)(qi)(qi)(qi)通過(guo)(guo)補汽(qi)(qi)(qi)(qi)閥注(zhu)入汽(qi)(qi)(qi)(qi)輪(lun)機(ji)中壓缸中間級(ji)，為(wei)機(ji)組(zu)提供(gong)3%Pe/min的(de)(de)升(sheng)負荷(he)速率。

熔(rong)(rong)鹽(yan)(yan)(yan)蒸(zheng)(zheng)汽發(fa)生系(xi)(xi)(xi)統(tong)(tong)提供3%Pe/min的(de)升負荷速(su)率(lv)的(de)過(guo)程(cheng)(cheng)(cheng)具有強(qiang)瞬態特性，為避免冷態啟(qi)動(dong)放熱(re)(re)對熔(rong)(rong)鹽(yan)(yan)(yan)系(xi)(xi)(xi)統(tong)(tong)的(de)熱(re)(re)沖(chong)擊，熔(rong)(rong)鹽(yan)(yan)(yan)系(xi)(xi)(xi)統(tong)(tong)設置了(le)動(dong)態保(bao)溫運行模式，即在非補汽工況下熔(rong)(rong)鹽(yan)(yan)(yan)蒸(zheng)(zheng)汽發(fa)生系(xi)(xi)(xi)統(tong)(tong)的(de)鹽(yan)(yan)(yan)側和水(shui)側均小流(liu)(liu)量(liang)運行，建立(li)和放熱(re)(re)相近(jin)的(de)溫度(du)場，使放熱(re)(re)過(guo)程(cheng)(cheng)(cheng)即時(shi)產汽注入汽輪機中(zhong)壓(ya)缸(gang)做功(gong)(gong)。熔(rong)(rong)鹽(yan)(yan)(yan)蒸(zheng)(zheng)汽發(fa)生系(xi)(xi)(xi)統(tong)(tong)放熱(re)(re)過(guo)程(cheng)(cheng)(cheng)中(zhong)為維持(chi)系(xi)(xi)(xi)統(tong)(tong)壓(ya)力和液位(wei)穩定，給水(shui)和蒸(zheng)(zheng)汽流(liu)(liu)量(liang)應匹配。由(you)圖(tu)2所(suo)示的(de)負荷變化(hua)曲線(xian)可知，負荷增(zeng)(zeng)大，所(suo)需蒸(zheng)(zheng)汽流(liu)(liu)量(liang)增(zeng)(zeng)加，對應的(de)熱(re)(re)量(liang)需求增(zeng)(zeng)加，熔(rong)(rong)鹽(yan)(yan)(yan)側的(de)流(liu)(liu)量(liang)也隨之(zhi)增(zeng)(zeng)大。總之(zhi)，為了(le)支撐3%Pe/min的(de)升負荷速(su)率(lv)，熔(rong)(rong)鹽(yan)(yan)(yan)和水(shui)側流(liu)(liu)量(liang)在幾分鐘內從動(dong)態保(bao)溫的(de)小流(liu)(liu)量(liang)增(zeng)(zeng)加到額定流(liu)(liu)量(liang)，對應放熱(re)(re)功(gong)(gong)率(lv)隨時(shi)間呈(cheng)三(san)角脈(mo)沖(chong)特征(zheng)，是(shi)典型的(de)強(qiang)瞬態過(guo)程(cheng)(cheng)(cheng)。

四、熔鹽對蒸汽發生系統影響的研究

4.1研究方法

本文的研(yan)(yan)究對象(xiang)是耦合(he)某350MW燃煤(mei)發電(dian)機(ji)組的熔(rong)鹽蒸汽發生(sheng)系(xi)統(tong)，以75%~100%THA升(sheng)(sheng)負荷過程設計工況作(zuo)為熔(rong)鹽選擇(ze)的研(yan)(yan)究基(ji)礎。受限于(yu)熔(rong)鹽系(xi)統(tong)承擔(dan)3%Pe/min升(sheng)(sheng)負荷速率需求及(ji)二元(yuan)鹽和三元(yuan)鹽物性(xing)參數，綜合(he)系(xi)統(tong)熱力計算與(yu)設備(bei)傳熱分析(xi)進行熔(rong)鹽比(bi)選及(ji)技(ji)術經(jing)濟性(xing)研(yan)(yan)究。

主要研究方法如(ru)(ru)下(xia)(如(ru)(ru)圖4)：

(1)根據(ju)3%Pe/min的(de)升負(fu)荷速率，結(jie)合汽(qi)(qi)輪機的(de)熱(re)力計(ji)算(suan)和熔(rong)鹽(yan)運(yun)行(xing)溫度(du)區間獲取所需蒸(zheng)汽(qi)(qi)和熔(rong)鹽(yan)流量，確定熔(rong)鹽(yan)蒸(zheng)汽(qi)(qi)發(fa)生(sheng)(sheng)系(xi)(xi)統(tong)T-Q圖(tu)。根據(ju)T-Q圖(tu)，在滿足(zu)蒸(zheng)汽(qi)(qi)發(fa)生(sheng)(sheng)系(xi)(xi)統(tong)換(huan)熱(re)器設計(ji)原則的(de)基礎上，通過熱(re)力計(ji)算(suan)得到熔(rong)鹽(yan)蒸(zheng)汽(qi)(qi)發(fa)生(sheng)(sheng)系(xi)(xi)統(tong)熱(re)平衡圖(tu)，明確各(ge)級換(huan)熱(re)器熱(re)負(fu)荷Q以及汽(qi)(qi)水側和熔(rong)鹽(yan)側溫度(du)、壓力、流量等參數。

(2)根(gen)(gen)據(ju)(ju)三元鹽(yan)(yan)和(he)二元鹽(yan)(yan)物性(xing)參數，結(jie)合現有文獻的實驗數據(ju)(ju)和(he)研究成果，選擇(ze)(ze)適合高溫(wen)熔鹽(yan)(yan)的傳(chuan)熱(re)及阻(zu)力(li)關聯式，借鑒成熟的汽水傳(chuan)熱(re)和(he)阻(zu)力(li)關聯式，確定熔鹽(yan)(yan)側(ce)(ce)和(he)汽水側(ce)(ce)傳(chuan)熱(re)系(xi)數、溫(wen)度和(he)阻(zu)力(li)參數等。根(gen)(gen)據(ju)(ju)上(shang)述研究結(jie)果，使用(yong)工程用(yong)成熟的HTRI軟件(jian)進行換熱(re)器選型和(he)設計，根(gen)(gen)據(ju)(ju)電(dian)網需求選擇(ze)(ze)合適的升(sheng)負荷次(ci)數，確定熔鹽(yan)(yan)用(yong)量(liang)。

在(zai)上(shang)述給定(ding)邊界條件下，進行三元鹽和(he)二元鹽蒸(zheng)汽(qi)發(fa)生系統(tong)技(ji)術性和(he)經(jing)濟(ji)性分析(xi)。

4.2熔鹽蒸汽發生系統的技術指標對比

耦合(he)燃(ran)煤發電(dian)機組的(de)熔鹽(yan)系(xi)統選用成熟的(de)二(er)(er)元鹽(yan)和(he)三元鹽(yan)作為(wei)儲熱(re)介質，表1為(wei)二(er)(er)元鹽(yan)和(he)三元鹽(yan)主要參數對比表，包括鹽(yan)的(de)成份、熔點、分解溫度、運行(xing)溫區(qu)、密度及價格。

由表1可知，三(san)(san)元(yuan)(yuan)(yuan)(yuan)鹽(yan)(yan)熔(rong)(rong)(rong)(rong)點和(he)(he)分(fen)解(jie)溫度(du)(du)分(fen)別(bie)為(wei)143℃和(he)(he)450℃，二(er)元(yuan)(yuan)(yuan)(yuan)鹽(yan)(yan)的(de)(de)熔(rong)(rong)(rong)(rong)點和(he)(he)分(fen)解(jie)溫度(du)(du)分(fen)別(bie)為(wei)220℃和(he)(he)585℃。耦(ou)合(he)燃煤發電(dian)的(de)(de)熔(rong)(rong)(rong)(rong)鹽(yan)(yan)蒸汽發生系統多(duo)為(wei)變工況(kuang)運(yun)(yun)(yun)行(xing)(xing)，為(wei)避免熔(rong)(rong)(rong)(rong)鹽(yan)(yan)凝固風(feng)險(xian)，二(er)元(yuan)(yuan)(yuan)(yuan)鹽(yan)(yan)及三(san)(san)元(yuan)(yuan)(yuan)(yuan)鹽(yan)(yan)運(yun)(yun)(yun)行(xing)(xing)溫度(du)(du)下限(xian)(xian)在熔(rong)(rong)(rong)(rong)點基礎(chu)上(shang)增加~90℃的(de)(de)裕度(du)(du)。同時為(wei)避免變工況(kuang)運(yun)(yun)(yun)行(xing)(xing)熔(rong)(rong)(rong)(rong)鹽(yan)(yan)局部(bu)分(fen)解(jie)風(feng)險(xian)，二(er)元(yuan)(yuan)(yuan)(yuan)鹽(yan)(yan)運(yun)(yun)(yun)行(xing)(xing)溫度(du)(du)上(shang)限(xian)(xian)在分(fen)解(jie)溫度(du)(du)基礎(chu)上(shang)下降(jiang)35℃，三(san)(san)元(yuan)(yuan)(yuan)(yuan)鹽(yan)(yan)運(yun)(yun)(yun)行(xing)(xing)溫度(du)(du)上(shang)限(xian)(xian)應控制(zhi)在400℃以(yi)內。確定二(er)元(yuan)(yuan)(yuan)(yuan)鹽(yan)(yan)運(yun)(yun)(yun)行(xing)(xing)溫度(du)(du)(310~550)℃，三(san)(san)元(yuan)(yuan)(yuan)(yuan)鹽(yan)(yan)運(yun)(yun)(yun)行(xing)(xing)溫度(du)(du)區間(jian)(230~390)℃。在給定溫度(du)(du)下(350℃)，二(er)元(yuan)(yuan)(yuan)(yuan)鹽(yan)(yan)和(he)(he)三(san)(san)元(yuan)(yuan)(yuan)(yuan)鹽(yan)(yan)的(de)(de)密度(du)(du)基本相同，分(fen)別(bie)為(wei)1867.4 kg/m3和(he)(he)1823.5 kg/m3。二(er)元(yuan)(yuan)(yuan)(yuan)鹽(yan)(yan)和(he)(he)三(san)(san)元(yuan)(yuan)(yuan)(yuan)鹽(yan)(yan)均(jun)為(wei)成熟的(de)(de)商業用鹽(yan)(yan)，三(san)(san)元(yuan)(yuan)(yuan)(yuan)鹽(yan)(yan)的(de)(de)價位(wei)略高(gao)。

為定量評估和對比二元鹽和三元鹽蒸(zheng)汽發(fa)生系統(tong)技(ji)術(shu)指標，定義熔鹽系統(tong)發(fa)電效率(hS?E)：

式(1)中(zhong)，PIP為補汽(qi)后的發(fa)(fa)電量，PB為基(ji)準負荷發(fa)(fa)電量，Phr為熔鹽蒸汽(qi)發(fa)(fa)生系統(tong)放熱功率:

式(2)中，GSI為(wei)(wei)補(bu)汽(qi)流量；h1為(wei)(wei)補(bu)汽(qi)焓值；h2為(wei)(wei)熔鹽蒸汽(qi)發(fa)生(sheng)系統(tong)(tong)給水(shui)焓值。設計(ji)工況下，設計(ji)工況下二元(yuan)鹽和(he)三元(yuan)鹽蒸汽(qi)發(fa)生(sheng)系統(tong)(tong)匯(hui)入汽(qi)輪(lun)機的蒸汽(qi)溫度(du)分(fen)別為(wei)(wei)~513℃和(he)~375℃。對應的熔鹽蒸汽(qi)發(fa)生(sheng)系統(tong)(tong)發(fa)電(dian)效率分(fen)別為(wei)(wei)36.7%和(he)29.2%，如圖5中虛線圈所示。

在實際(ji)工程中，熱(re)鹽(yan)罐中熱(re)鹽(yan)溫度直接影響熔鹽(yan)蒸汽發生系統的產汽溫度。影響熱(re)鹽(yan)溫度的因(yin)素(su)主要包括(kuo)：

(1)儲熱(re)(re)過(guo)程中(zhong)產生(sheng)的(de)熱(re)(re)鹽(yan)溫度存在偏差；

(2)放置(zhi)過程中熱鹽罐散熱引起的溫降；

(3)蒸(zheng)汽管道散(san)熱和壓降引(yin)起(qi)的溫降等。

上述(shu)原因均(jun)會導致熔(rong)(rong)(rong)鹽(yan)(yan)蒸(zheng)(zheng)(zheng)汽(qi)(qi)(qi)發(fa)生(sheng)系(xi)(xi)統(tong)(tong)產生(sheng)蒸(zheng)(zheng)(zheng)汽(qi)(qi)(qi)溫(wen)(wen)(wen)度(du)的(de)波動。為(wei)保證蒸(zheng)(zheng)(zheng)汽(qi)(qi)(qi)溫(wen)(wen)(wen)度(du)符合汽(qi)(qi)(qi)輪(lun)起的(de)要(yao)求(qiu)，熔(rong)(rong)(rong)鹽(yan)(yan)蒸(zheng)(zheng)(zheng)汽(qi)(qi)(qi)發(fa)生(sheng)系(xi)(xi)統(tong)(tong)產生(sheng)蒸(zheng)(zheng)(zheng)汽(qi)(qi)(qi)溫(wen)(wen)(wen)度(du)的(de)允(yun)許偏差為(wei)設計溫(wen)(wen)(wen)度(du)的(de)±10℃。熔(rong)(rong)(rong)鹽(yan)(yan)蒸(zheng)(zheng)(zheng)汽(qi)(qi)(qi)發(fa)生(sheng)系(xi)(xi)統(tong)(tong)發(fa)電(dian)(dian)(dian)效率隨產汽(qi)(qi)(qi)溫(wen)(wen)(wen)度(du)的(de)變化如圖(tu)(tu)5所示(shi)。由圖(tu)(tu)可知，隨著蒸(zheng)(zheng)(zheng)汽(qi)(qi)(qi)溫(wen)(wen)(wen)度(du)的(de)增加(jia)(jia)，熔(rong)(rong)(rong)鹽(yan)(yan)蒸(zheng)(zheng)(zheng)汽(qi)(qi)(qi)發(fa)生(sheng)系(xi)(xi)統(tong)(tong)發(fa)電(dian)(dian)(dian)效率呈線性增加(jia)(jia)趨勢(shi)。當(dang)三元(yuan)鹽(yan)(yan)蒸(zheng)(zheng)(zheng)汽(qi)(qi)(qi)發(fa)生(sheng)系(xi)(xi)統(tong)(tong)產汽(qi)(qi)(qi)溫(wen)(wen)(wen)度(du)由365℃升高(gao)到(dao)385℃，對應熔(rong)(rong)(rong)鹽(yan)(yan)系(xi)(xi)統(tong)(tong)的(de)發(fa)電(dian)(dian)(dian)效率從28.9%增加(jia)(jia)到(dao)29.4%，平(ping)均(jun)發(fa)電(dian)(dian)(dian)效率為(wei)29.2%；二元(yuan)鹽(yan)(yan)蒸(zheng)(zheng)(zheng)汽(qi)(qi)(qi)發(fa)生(sheng)系(xi)(xi)統(tong)(tong)產汽(qi)(qi)(qi)溫(wen)(wen)(wen)度(du)由503℃升高(gao)到(dao)523℃時，對應熔(rong)(rong)(rong)鹽(yan)(yan)系(xi)(xi)統(tong)(tong)的(de)發(fa)電(dian)(dian)(dian)效率從36.5%增加(jia)(jia)到(dao)36.9%，平(ping)均(jun)發(fa)電(dian)(dian)(dian)效率為(wei)36.7%。

綜上所述，三元鹽(yan)蒸(zheng)汽發生(sheng)(sheng)系統產生(sheng)(sheng)的(de)蒸(zheng)汽溫度比(bi)二元鹽(yan)低(di)，注入汽輪機的(de)位置(zhi)更靠后，對應較低(di)的(de)發電效率。

在(zai)機(ji)(ji)(ji)(ji)組(zu)高負(fu)(fu)荷段(50%~100%THA)，根據燃煤機(ji)(ji)(ji)(ji)組(zu)實際(ji)調峰運行(xing)情況，將(jiang)熔(rong)鹽(yan)系(xi)統在(zai)單(dan)次升(sheng)負(fu)(fu)荷范圍定位X→X+25%Pe(X為(wei)50%THA~75%THA)。以75%THA~100%THA升(sheng)負(fu)(fu)荷范圍為(wei)例，為(wei)實現燃煤機(ji)(ji)(ji)(ji)組(zu)6%Pe/min的(de)升(sheng)負(fu)(fu)荷速(su)率(圖6a-b中(zhong)的(de)黑線)，燃煤機(ji)(ji)(ji)(ji)組(zu)的(de)鍋爐按照3%Pe/min的(de)速(su)率線性(xing)升(sheng)負(fu)(fu)荷到(dao)(dao)機(ji)(ji)(ji)(ji)組(zu)目標負(fu)(fu)荷(圖6a-b中(zhong)的(de)藍線)，熔(rong)鹽(yan)蒸(zheng)汽(qi)(qi)(qi)(qi)發生(sheng)(sheng)系(xi)統以3%Pe/min速(su)率升(sheng)到(dao)(dao)峰值后逐漸降(jiang)低負(fu)(fu)荷直(zhi)至退出，熔(rong)鹽(yan)蒸(zheng)汽(qi)(qi)(qi)(qi)發生(sheng)(sheng)系(xi)統熱功率呈(cheng)現三角形變化趨勢(shi)(圖6a-b中(zhong)的(de)紅(hong)線)。二元鹽(yan)相比于(yu)三元鹽(yan)運行(xing)溫度高，能產(chan)生(sheng)(sheng)更高溫度的(de)蒸(zheng)汽(qi)(qi)(qi)(qi)，在(zai)汽(qi)(qi)(qi)(qi)輪機(ji)(ji)(ji)(ji)中(zhong)壓缸確定溫度匹配的(de)匯入點，對應蒸(zheng)汽(qi)(qi)(qi)(qi)壓力(li)也(ye)高。

因此，二元鹽(yan)(yan)(yan)(yan)(yan)蒸(zheng)(zheng)(zheng)汽(qi)(qi)發(fa)(fa)生(sheng)(sheng)系(xi)統(tong)(tong)能產生(sheng)(sheng)更(geng)高品位蒸(zheng)(zheng)(zheng)汽(qi)(qi)。考慮熔鹽(yan)(yan)(yan)(yan)(yan)蒸(zheng)(zheng)(zheng)汽(qi)(qi)發(fa)(fa)生(sheng)(sheng)系(xi)統(tong)(tong)匯入汽(qi)(qi)輪機(ji)過(guo)程中節(jie)流損失(shi)引起的(de)溫降，確定(ding)二元鹽(yan)(yan)(yan)(yan)(yan)和(he)三元鹽(yan)(yan)(yan)(yan)(yan)蒸(zheng)(zheng)(zheng)汽(qi)(qi)發(fa)(fa)生(sheng)(sheng)系(xi)統(tong)(tong)產生(sheng)(sheng)的(de)蒸(zheng)(zheng)(zheng)汽(qi)(qi)分別匯入中壓缸(gang)5級后和(he)中壓缸(gang)13級后。二元鹽(yan)(yan)(yan)(yan)(yan)比三元鹽(yan)(yan)(yan)(yan)(yan)產生(sheng)(sheng)蒸(zheng)(zheng)(zheng)汽(qi)(qi)在汽(qi)(qi)輪機(ji)的(de)匯入點更(geng)靠(kao)前，定(ding)性上進一步說明二元鹽(yan)(yan)(yan)(yan)(yan)蒸(zheng)(zheng)(zheng)汽(qi)(qi)發(fa)(fa)生(sheng)(sheng)系(xi)統(tong)(tong)能量利用效(xiao)率(lv)優于三元鹽(yan)(yan)(yan)(yan)(yan)蒸(zheng)(zheng)(zheng)汽(qi)(qi)發(fa)(fa)生(sheng)(sheng)系(xi)統(tong)(tong)。根據(ju)熔鹽(yan)(yan)(yan)(yan)(yan)蒸(zheng)(zheng)(zheng)汽(qi)(qi)發(fa)(fa)生(sheng)(sheng)系(xi)統(tong)(tong)設計工況發(fa)(fa)電效(xiao)率(lv)及3%Pe/min升負荷速(su)率(lv)要(yao)求，確定(ding)二元鹽(yan)(yan)(yan)(yan)(yan)和(he)三元鹽(yan)(yan)(yan)(yan)(yan)蒸(zheng)(zheng)(zheng)汽(qi)(qi)發(fa)(fa)生(sheng)(sheng)系(xi)統(tong)(tong)的(de)峰值熱功率(lv)分別為136.5 MW和(he)165.8 MW(詳見圖(tu)6a-b)。

針對熔(rong)鹽(yan)(yan)蒸(zheng)汽(qi)發生(sheng)系(xi)(xi)統(tong)，考(kao)(kao)慮系(xi)(xi)統(tong)運(yun)行效率、安(an)全性(xing)(xing)和系(xi)(xi)統(tong)經濟性(xing)(xing)等多方面因(yin)素，合理確(que)定熱(re)鹽(yan)(yan)/冷(leng)(leng)(leng)(leng)鹽(yan)(yan)溫(wen)度(du)(du)(du)(du)、匯(hui)汽(qi)點(dian)參(can)數、給水(shui)點(dian)位置(zhi)及參(can)數和蒸(zheng)汽(qi)發生(sheng)系(xi)(xi)統(tong)壓力，如(ru)圖6c-d所示(shi)。熱(re)鹽(yan)(yan)溫(wen)度(du)(du)(du)(du)越(yue)(yue)高/冷(leng)(leng)(leng)(leng)鹽(yan)(yan)溫(wen)度(du)(du)(du)(du)越(yue)(yue)低，單位質量(liang)熔(rong)鹽(yan)(yan)儲熱(re)容量(liang)越(yue)(yue)高，熔(rong)鹽(yan)(yan)用量(liang)越(yue)(yue)少，蒸(zheng)汽(qi)發生(sheng)系(xi)(xi)統(tong)運(yun)行時熱(re)鹽(yan)(yan)泵的(de)功耗(hao)減低，從系(xi)(xi)統(tong)效率及運(yun)行成本考(kao)(kao)慮，應盡量(liang)提高熱(re)鹽(yan)(yan)溫(wen)度(du)(du)(du)(du)/降低冷(leng)(leng)(leng)(leng)鹽(yan)(yan)溫(wen)度(du)(du)(du)(du)。從熔(rong)鹽(yan)(yan)安(an)全性(xing)(xing)和系(xi)(xi)統(tong)經濟性(xing)(xing)兩方面考(kao)(kao)慮，二元(yuan)(yuan)鹽(yan)(yan)和三元(yuan)(yuan)鹽(yan)(yan)蒸(zheng)汽(qi)發生(sheng)系(xi)(xi)統(tong)的(de)熱(re)鹽(yan)(yan)溫(wen)度(du)(du)(du)(du)分別(bie)設置(zhi)為550℃(如(ru)圖6c的(de)A點(dian)所示(shi))和390℃(如(ru)圖6d的(de)A'點(dian)所示(shi))。冷(leng)(leng)(leng)(leng)鹽(yan)(yan)溫(wen)度(du)(du)(du)(du)的(de)選擇受熔(rong)鹽(yan)(yan)凝固(gu)溫(wen)度(du)(du)(du)(du)和蒸(zheng)發器入口傳熱(re)窄點(dian)溫(wen)差限制，冷(leng)(leng)(leng)(leng)鹽(yan)(yan)的(de)溫(wen)度(du)(du)(du)(du)在熔(rong)點(dian)基礎上增(zeng)加~90℃的(de)裕度(du)(du)(du)(du)，確(que)定二元(yuan)(yuan)鹽(yan)(yan)和三元(yuan)(yuan)鹽(yan)(yan)蒸(zheng)汽(qi)發生(sheng)系(xi)(xi)統(tong)的(de)冷(leng)(leng)(leng)(leng)鹽(yan)(yan)溫(wen)度(du)(du)(du)(du)分別(bie)為235℃(如(ru)圖6c的(de)B點(dian)所示(shi))和310℃(如(ru)圖6d的(de)B'點(dian)所示(shi))。

為(wei)(wei)(wei)提(ti)高機(ji)(ji)組運行效率，熔(rong)(rong)(rong)鹽(yan)(yan)(yan)蒸(zheng)(zheng)(zheng)(zheng)汽(qi)(qi)(qi)(qi)(qi)發(fa)生(sheng)(sheng)(sheng)(sheng)系(xi)(xi)統(tong)(tong)(tong)(tong)(tong)產汽(qi)(qi)(qi)(qi)(qi)匯(hui)(hui)入(ru)(ru)點(dian)(dian)應(ying)(ying)(ying)(ying)盡量在汽(qi)(qi)(qi)(qi)(qi)輪機(ji)(ji)的(de)(de)靠(kao)前(qian)位置。根據(ju)流動傳熱(re)(re)(re)學原理(li)，產汽(qi)(qi)(qi)(qi)(qi)溫(wen)(wen)(wen)度(du)由熱(re)(re)(re)鹽(yan)(yan)(yan)溫(wen)(wen)(wen)度(du)及過(guo)熱(re)(re)(re)器出口端差共(gong)同決定(ding)(ding)。根據(ju)換熱(re)(re)(re)器設計(ji)原則(ze)，過(guo)熱(re)(re)(re)器出口端差應(ying)(ying)(ying)(ying)>10℃，同時為(wei)(wei)(wei)匹配(pei)合(he)適(shi)的(de)(de)匯(hui)(hui)汽(qi)(qi)(qi)(qi)(qi)位置，設定(ding)(ding)二(er)元(yuan)鹽(yan)(yan)(yan)和(he)(he)三元(yuan)鹽(yan)(yan)(yan)蒸(zheng)(zheng)(zheng)(zheng)汽(qi)(qi)(qi)(qi)(qi)發(fa)生(sheng)(sheng)(sheng)(sheng)系(xi)(xi)統(tong)(tong)(tong)(tong)(tong)過(guo)熱(re)(re)(re)器出口蒸(zheng)(zheng)(zheng)(zheng)汽(qi)(qi)(qi)(qi)(qi)溫(wen)(wen)(wen)度(du)分別(bie)為(wei)(wei)(wei)516℃(如(ru)圖6c的(de)(de)C點(dian)(dian)所示)和(he)(he)378℃(如(ru)圖6d的(de)(de)C'點(dian)(dian)所示)。熔(rong)(rong)(rong)鹽(yan)(yan)(yan)蒸(zheng)(zheng)(zheng)(zheng)汽(qi)(qi)(qi)(qi)(qi)發(fa)生(sheng)(sheng)(sheng)(sheng)系(xi)(xi)統(tong)(tong)(tong)(tong)(tong)運行時，給(gei)(gei)水(shui)(shui)(shui)從原燃煤機(ji)(ji)組取(qu)水(shui)(shui)(shui)，加熱(re)(re)(re)為(wei)(wei)(wei)過(guo)熱(re)(re)(re)蒸(zheng)(zheng)(zheng)(zheng)汽(qi)(qi)(qi)(qi)(qi)匯(hui)(hui)入(ru)(ru)汽(qi)(qi)(qi)(qi)(qi)輪機(ji)(ji)。為(wei)(wei)(wei)了減少對(dui)原機(ji)(ji)組的(de)(de)影響，取(qu)水(shui)(shui)(shui)點(dian)(dian)應(ying)(ying)(ying)(ying)設置在大(da)容器內，例如(ru)凝結水(shui)(shui)(shui)井(jing)和(he)(he)除氧器。凝結水(shui)(shui)(shui)溫(wen)(wen)(wen)遠低于(yu)熔(rong)(rong)(rong)鹽(yan)(yan)(yan)熔(rong)(rong)(rong)點(dian)(dian)，需(xu)(xu)要對(dui)給(gei)(gei)水(shui)(shui)(shui)進行預(yu)熱(re)(re)(re)，否(fou)則(ze)將導(dao)致熔(rong)(rong)(rong)鹽(yan)(yan)(yan)凝固，不(bu)能(neng)作為(wei)(wei)(wei)熔(rong)(rong)(rong)鹽(yan)(yan)(yan)蒸(zheng)(zheng)(zheng)(zheng)汽(qi)(qi)(qi)(qi)(qi)發(fa)生(sheng)(sheng)(sheng)(sheng)系(xi)(xi)統(tong)(tong)(tong)(tong)(tong)給(gei)(gei)水(shui)(shui)(shui)。因此，選取(qu)除氧器為(wei)(wei)(wei)熔(rong)(rong)(rong)鹽(yan)(yan)(yan)系(xi)(xi)統(tong)(tong)(tong)(tong)(tong)給(gei)(gei)水(shui)(shui)(shui)源，設置獨(du)立給(gei)(gei)水(shui)(shui)(shui)泵取(qu)水(shui)(shui)(shui)，設計(ji)工況下給(gei)(gei)水(shui)(shui)(shui)溫(wen)(wen)(wen)度(du)為(wei)(wei)(wei)198.5℃，大(da)于(yu)三元(yuan)鹽(yan)(yan)(yan)熔(rong)(rong)(rong)點(dian)(dian)溫(wen)(wen)(wen)度(du)，不(bu)存(cun)在熔(rong)(rong)(rong)鹽(yan)(yan)(yan)凝固風(feng)險(xian)，但小于(yu)二(er)元(yuan)鹽(yan)(yan)(yan)熔(rong)(rong)(rong)點(dian)(dian)溫(wen)(wen)(wen)度(du)，二(er)元(yuan)鹽(yan)(yan)(yan)需(xu)(xu)要抽汽(qi)(qi)(qi)(qi)(qi)對(dui)給(gei)(gei)水(shui)(shui)(shui)進行預(yu)熱(re)(re)(re)，二(er)元(yuan)鹽(yan)(yan)(yan)和(he)(he)三元(yuan)鹽(yan)(yan)(yan)蒸(zheng)(zheng)(zheng)(zheng)汽(qi)(qi)(qi)(qi)(qi)發(fa)生(sheng)(sheng)(sheng)(sheng)系(xi)(xi)統(tong)(tong)(tong)(tong)(tong)蒸(zheng)(zheng)(zheng)(zheng)發(fa)器入(ru)(ru)口水(shui)(shui)(shui)溫(wen)(wen)(wen)如(ru)圖6c的(de)(de)D點(dian)(dian)和(he)(he)圖6d的(de)(de)D'點(dian)(dian)所示。熔(rong)(rong)(rong)鹽(yan)(yan)(yan)蒸(zheng)(zheng)(zheng)(zheng)汽(qi)(qi)(qi)(qi)(qi)發(fa)生(sheng)(sheng)(sheng)(sheng)系(xi)(xi)統(tong)(tong)(tong)(tong)(tong)產生(sheng)(sheng)(sheng)(sheng)的(de)(de)蒸(zheng)(zheng)(zheng)(zheng)汽(qi)(qi)(qi)(qi)(qi)壓(ya)(ya)(ya)力(li)(li)決定(ding)(ding)了匯(hui)(hui)入(ru)(ru)汽(qi)(qi)(qi)(qi)(qi)輪機(ji)(ji)位置和(he)(he)蒸(zheng)(zheng)(zheng)(zheng)發(fa)器的(de)(de)熱(re)(re)(re)負荷，并通過(guo)蒸(zheng)(zheng)(zheng)(zheng)發(fa)器入(ru)(ru)口傳熱(re)(re)(re)窄點(dian)(dian)溫(wen)(wen)(wen)差限制(zhi)冷鹽(yan)(yan)(yan)溫(wen)(wen)(wen)度(du)。為(wei)(wei)(wei)了使熔(rong)(rong)(rong)鹽(yan)(yan)(yan)蒸(zheng)(zheng)(zheng)(zheng)汽(qi)(qi)(qi)(qi)(qi)發(fa)生(sheng)(sheng)(sheng)(sheng)系(xi)(xi)統(tong)(tong)(tong)(tong)(tong)和(he)(he)汽(qi)(qi)(qi)(qi)(qi)輪機(ji)(ji)最大(da)程度(du)上解耦，補汽(qi)(qi)(qi)(qi)(qi)閥后與閥前(qian)壓(ya)(ya)(ya)力(li)(li)的(de)(de)比(bi)值應(ying)(ying)(ying)(ying)小于(yu)0.546，滿(man)足(zu)蒸(zheng)(zheng)(zheng)(zheng)汽(qi)(qi)(qi)(qi)(qi)臨界流動特性，使蒸(zheng)(zheng)(zheng)(zheng)汽(qi)(qi)(qi)(qi)(qi)流量不(bu)受閥后壓(ya)(ya)(ya)力(li)(li)限制(zhi)。二(er)元(yuan)鹽(yan)(yan)(yan)和(he)(he)三元(yuan)鹽(yan)(yan)(yan)蒸(zheng)(zheng)(zheng)(zheng)汽(qi)(qi)(qi)(qi)(qi)發(fa)生(sheng)(sheng)(sheng)(sheng)系(xi)(xi)統(tong)(tong)(tong)(tong)(tong)匯(hui)(hui)入(ru)(ru)汽(qi)(qi)(qi)(qi)(qi)輪機(ji)(ji)位置對(dui)應(ying)(ying)(ying)(ying)壓(ya)(ya)(ya)力(li)(li)分別(bie)為(wei)(wei)(wei)3.4 MPa和(he)(he)1.49 MPa，確定(ding)(ding)閥前(qian)蒸(zheng)(zheng)(zheng)(zheng)汽(qi)(qi)(qi)(qi)(qi)發(fa)生(sheng)(sheng)(sheng)(sheng)系(xi)(xi)統(tong)(tong)(tong)(tong)(tong)的(de)(de)壓(ya)(ya)(ya)力(li)(li)分別(bie)為(wei)(wei)(wei)6.23 MPa和(he)(he)2.73 MPa。蒸(zheng)(zheng)(zheng)(zheng)發(fa)器壓(ya)(ya)(ya)力(li)(li)設計(ji)值需(xu)(xu)高于(yu)匯(hui)(hui)汽(qi)(qi)(qi)(qi)(qi)所需(xu)(xu)的(de)(de)最低壓(ya)(ya)(ya)力(li)(li)，在滿(man)足(zu)不(bu)小于(yu)8℃傳熱(re)(re)(re)窄點(dian)(dian)溫(wen)(wen)(wen)差的(de)(de)前(qian)提(ti)下，壓(ya)(ya)(ya)力(li)(li)應(ying)(ying)(ying)(ying)盡可能(neng)高，避(bi)免兩相流不(bu)穩定(ding)(ding)性，同時需(xu)(xu)考慮承壓(ya)(ya)(ya)能(neng)力(li)(li)對(dui)設備投資的(de)(de)影響。最終確定(ding)(ding)二(er)元(yuan)鹽(yan)(yan)(yan)和(he)(he)三元(yuan)鹽(yan)(yan)(yan)蒸(zheng)(zheng)(zheng)(zheng)汽(qi)(qi)(qi)(qi)(qi)發(fa)生(sheng)(sheng)(sheng)(sheng)系(xi)(xi)統(tong)(tong)(tong)(tong)(tong)壓(ya)(ya)(ya)力(li)(li)分別(bie)為(wei)(wei)(wei)6.9 MPa和(he)(he)3.29 MPa。

美國(guo)(guo)圣地安國(guo)(guo)家實(shi)驗(yan)室報(bao)告中給出(chu)了二(er)元(yuan)(yuan)(yuan)鹽(yan)(yan)密(mi)度(du)(du)(du)(du)、粘(zhan)度(du)(du)(du)(du)、導熱系(xi)(xi)數(shu)(shu)、比熱數(shu)(shu)據及計算(suan)公式，與(yu)物(wu)性(xing)計算(suan)方法(fa)基本(ben)相符，同時二(er)元(yuan)(yuan)(yuan)鹽(yan)(yan)的(de)(de)(de)(de)(de)物(wu)性(xing)也通過實(shi)驗(yan)數(shu)(shu)據得(de)到了驗(yan)證(zheng)。給出(chu)了三元(yuan)(yuan)(yuan)鹽(yan)(yan)的(de)(de)(de)(de)(de)密(mi)度(du)(du)(du)(du)、粘(zhan)度(du)(du)(du)(du)、導熱系(xi)(xi)數(shu)(shu)和(he)(he)(he)比熱容等參(can)數(shu)(shu)的(de)(de)(de)(de)(de)計算(suan)公式。圖(tu)(tu)7匯總了二(er)元(yuan)(yuan)(yuan)鹽(yan)(yan)和(he)(he)(he)三元(yuan)(yuan)(yuan)鹽(yan)(yan)物(wu)性(xing)(μ、λ、cp和(he)(he)(he)Pr)隨(sui)溫(wen)(wen)(wen)度(du)(du)(du)(du)的(de)(de)(de)(de)(de)變化趨勢(shi)。由圖(tu)(tu)可(ke)知，二(er)元(yuan)(yuan)(yuan)鹽(yan)(yan)和(he)(he)(he)三元(yuan)(yuan)(yuan)鹽(yan)(yan)在(zai)運行溫(wen)(wen)(wen)度(du)(du)(du)(du)區間內(nei)粘(zhan)度(du)(du)(du)(du)μ隨(sui)溫(wen)(wen)(wen)度(du)(du)(du)(du)增(zeng)(zeng)加(jia)(jia)呈快(kuai)速(su)降低，隨(sui)后逐漸(jian)趨向平緩的(de)(de)(de)(de)(de)變化趨勢(shi)，交叉溫(wen)(wen)(wen)度(du)(du)(du)(du)范圍內(nei)兩種熔(rong)鹽(yan)(yan)的(de)(de)(de)(de)(de)μ重疊，如(ru)圖(tu)(tu)7a。熔(rong)鹽(yan)(yan)的(de)(de)(de)(de)(de)成份影響(xiang)導熱系(xi)(xi)數(shu)(shu)λ、比熱容cp和(he)(he)(he)普朗特數(shu)(shu)Pr隨(sui)溫(wen)(wen)(wen)度(du)(du)(du)(du)的(de)(de)(de)(de)(de)變化趨勢(shi)。二(er)元(yuan)(yuan)(yuan)鹽(yan)(yan)λ隨(sui)溫(wen)(wen)(wen)度(du)(du)(du)(du)增(zeng)(zeng)加(jia)(jia)而增(zeng)(zeng)大，三元(yuan)(yuan)(yuan)鹽(yan)(yan)導熱系(xi)(xi)數(shu)(shu)λ隨(sui)溫(wen)(wen)(wen)度(du)(du)(du)(du)增(zeng)(zeng)加(jia)(jia)呈下降變化趨勢(shi)，如(ru)圖(tu)(tu)7b。二(er)元(yuan)(yuan)(yuan)鹽(yan)(yan)cp隨(sui)溫(wen)(wen)(wen)度(du)(du)(du)(du)增(zeng)(zeng)大線性(xing)增(zeng)(zeng)加(jia)(jia)，而三元(yuan)(yuan)(yuan)鹽(yan)(yan)比熱容則不受溫(wen)(wen)(wen)度(du)(du)(du)(du)影響(xiang)，在(zai)各溫(wen)(wen)(wen)度(du)(du)(du)(du)下均為(wei)常(chang)數(shu)(shu)~1.56 kJ/(kg·K)，如(ru)圖(tu)(tu)7c。二(er)元(yuan)(yuan)(yuan)鹽(yan)(yan)和(he)(he)(he)三元(yuan)(yuan)(yuan)鹽(yan)(yan)的(de)(de)(de)(de)(de)Pr隨(sui)溫(wen)(wen)(wen)度(du)(du)(du)(du)的(de)(de)(de)(de)(de)增(zeng)(zeng)加(jia)(jia)呈下降趨勢(shi)，兩種鹽(yan)(yan)的(de)(de)(de)(de)(de)變化趨勢(shi)一(yi)致，且二(er)元(yuan)(yuan)(yuan)鹽(yan)(yan)的(de)(de)(de)(de)(de)Pr值僅為(wei)三元(yuan)(yuan)(yuan)鹽(yan)(yan)的(de)(de)(de)(de)(de)2/3,如(ru)圖(tu)(tu)7d。

在熔鹽(yan)(yan)(yan)蒸汽發(fa)生系統換(huan)熱(re)(re)(re)(re)(re)(re)器(qi)(qi)熱(re)(re)(re)(re)(re)(re)力計算過程中(zhong)，汽水側傳熱(re)(re)(re)(re)(re)(re)系數研究(jiu)較為(wei)成(cheng)熟，因此選(xuan)擇準確的(de)(de)(de)熔鹽(yan)(yan)(yan)傳熱(re)(re)(re)(re)(re)(re)系數計算公式極為(wei)重要。由4.3節的(de)(de)(de)描述(shu)可(ke)以得到，二元(yuan)鹽(yan)(yan)(yan)蒸汽發(fa)生器(qi)(qi)系統中(zhong)預熱(re)(re)(re)(re)(re)(re)器(qi)(qi)、蒸發(fa)器(qi)(qi)和(he)過熱(re)(re)(re)(re)(re)(re)器(qi)(qi)的(de)(de)(de)選(xuan)型分(fen)別為(wei)BEU、BEU和(he)HAP，三元(yuan)鹽(yan)(yan)(yan)蒸汽發(fa)生器(qi)(qi)系統中(zhong)預熱(re)(re)(re)(re)(re)(re)器(qi)(qi)、蒸發(fa)器(qi)(qi)和(he)過熱(re)(re)(re)(re)(re)(re)器(qi)(qi)的(de)(de)(de)選(xuan)型分(fen)別為(wei)BGU、BEU和(he)HAP。

上述(shu)所(suo)有熔鹽(yan)(yan)汽水(shui)換熱(re)器(qi)均為管殼式(shi)換熱(re)器(qi)，根據(ju)兩側(ce)工質壓(ya)力的(de)(de)不同(tong)，對管側(ce)和殼側(ce)介(jie)質進行(xing)分配。其中熔鹽(yan)(yan)側(ce)壓(ya)力低，走殼側(ce)；汽水(shui)側(ce)壓(ya)力高，走管側(ce)。同(tong)時(shi)為了增強傳熱(re)系統(tong)，在(zai)殼側(ce)加裝折(zhe)流(liu)板(ban)擾(rao)流(liu)結構(gou)。現有研究能描(miao)(miao)述(shu)熔鹽(yan)(yan)在(zai)殼側(ce)流(liu)動時(shi)的(de)(de)傳熱(re)特性關(guan)聯式(shi)少，很(hen)多文獻(xian)是根據(ju)自己的(de)(de)實(shi)驗數據(ju)進行(xing)關(guan)聯式(shi)擬(ni)合。關(guan)于二(er)元鹽(yan)(yan)和三元鹽(yan)(yan)在(zai)帶擾(rao)流(liu)結構(gou)的(de)(de)殼側(ce)流(liu)動時(shi)的(de)(de)實(shi)驗數據(ju)較(jiao)少，圖8中給出(chu)的(de)(de)Kern關(guan)聯式(shi)(3)為描(miao)(miao)述(shu)流(liu)體在(zai)帶弓(gong)形折(zhe)流(liu)板(ban)的(de)(de)殼側(ce)流(liu)動時(shi)的(de)(de)傳統(tong)傳熱(re)關(guan)聯式(shi)。

由于本文(wen)研究的(de)熔(rong)鹽汽(qi)水(shui)換(huan)熱(re)器(qi)均為帶折流板的(de)管殼式換(huan)熱(re)器(qi)，可以采(cai)用Kern關聯式進(jin)行熔(rong)鹽傳熱(re)分析，具體的(de)Nu計算公式如下：

式(shi)(3)中(zhong)，Re為雷(lei)諾(nuo)(nuo)數(shu)(shu)(shu)(shu)，Pr為普朗(lang)特數(shu)(shu)(shu)(shu)，m f為流(liu)體(ti)平均溫度(du)計(ji)算流(liu)體(ti)的粘(zhan)度(du)，mw為壁(bi)面溫度(du)計(ji)算流(liu)體(ti)的粘(zhan)度(du)。由于熔(rong)鹽(yan)流(liu)動阻(zu)(zu)力(li)(li)測(ce)量(liang)難(nan)度(du)大(da)，引壓管內(nei)低(di)溫熔(rong)鹽(yan)易凝固(gu)，難(nan)以獲得準確的實驗測(ce)量(liang)數(shu)(shu)(shu)(shu)據(ju)。因此(ci)尚(shang)未在公(gong)(gong)開發表文獻中(zhong)檢索到關于熔(rong)鹽(yan)流(liu)動阻(zu)(zu)力(li)(li)的測(ce)量(liang)數(shu)(shu)(shu)(shu)據(ju)。通常認為熔(rong)鹽(yan)的流(liu)動特性(xing)較好，與純水(shui)相比(bi)只是粘(zhan)度(du)有所增大(da)。因此(ci)，可以選擇單相水(shui)的阻(zu)(zu)力(li)(li)系數(shu)(shu)(shu)(shu)公(gong)(gong)式(shi)近似計(ji)算熔(rong)鹽(yan)的摩擦阻(zu)(zu)力(li)(li)系數(shu)(shu)(shu)(shu)。當(dang)雷(lei)諾(nuo)(nuo)數(shu)(shu)(shu)(shu)低(di)于2300時，阻(zu)(zu)力(li)(li)系數(shu)(shu)(shu)(shu)的計(ji)算公(gong)(gong)式(shi)：

4.3熔鹽蒸汽發生系統流程及換熱器選型對比

熔(rong)(rong)(rong)(rong)(rong)鹽(yan)(yan)(yan)蒸汽(qi)(qi)發(fa)生(sheng)系(xi)(xi)統(tong)(tong)(tong)包括熔(rong)(rong)(rong)(rong)(rong)鹽(yan)(yan)(yan)和汽(qi)(qi)水(shui)兩個工(gong)質回(hui)路。對(dui)于(yu)(yu)熔(rong)(rong)(rong)(rong)(rong)鹽(yan)(yan)(yan)側(ce)，熱(re)(re)(re)鹽(yan)(yan)(yan)罐(guan)中(zhong)高溫(wen)熔(rong)(rong)(rong)(rong)(rong)鹽(yan)(yan)(yan)在(zai)熱(re)(re)(re)鹽(yan)(yan)(yan)泵驅動(dong)下(xia)，依(yi)(yi)次流經(jing)熔(rong)(rong)(rong)(rong)(rong)鹽(yan)(yan)(yan)汽(qi)(qi)水(shui)過熱(re)(re)(re)器(qi)、蒸發(fa)器(qi)和預熱(re)(re)(re)器(qi)釋放熱(re)(re)(re)量(liang)，冷(leng)卻后的(de)熔(rong)(rong)(rong)(rong)(rong)鹽(yan)(yan)(yan)送至(zhi)冷(leng)鹽(yan)(yan)(yan)罐(guan)。對(dui)于(yu)(yu)汽(qi)(qi)水(shui)側(ce)，熔(rong)(rong)(rong)(rong)(rong)鹽(yan)(yan)(yan)系(xi)(xi)統(tong)(tong)(tong)給(gei)(gei)(gei)水(shui)泵從(cong)除氧(yang)器(qi)取(qu)水(shui)，依(yi)(yi)次流經(jing)各(ge)級換熱(re)(re)(re)器(qi)，與熔(rong)(rong)(rong)(rong)(rong)鹽(yan)(yan)(yan)逆(ni)流換熱(re)(re)(re)加(jia)熱(re)(re)(re)成為過熱(re)(re)(re)蒸汽(qi)(qi)，匯入到汽(qi)(qi)輪機中(zhong)壓缸中(zhong)間級做功。熔(rong)(rong)(rong)(rong)(rong)鹽(yan)(yan)(yan)蒸汽(qi)(qi)發(fa)生(sheng)系(xi)(xi)統(tong)(tong)(tong)的(de)給(gei)(gei)(gei)水(shui)來(lai)自除氧(yang)器(qi)，設計工(gong)況下(xia)的(de)給(gei)(gei)(gei)水(shui)溫(wen)度198.5℃，低于(yu)(yu)二元鹽(yan)(yan)(yan)的(de)熔(rong)(rong)(rong)(rong)(rong)點。因此，二元鹽(yan)(yan)(yan)蒸汽(qi)(qi)發(fa)生(sheng)系(xi)(xi)統(tong)(tong)(tong)需增設給(gei)(gei)(gei)水(shui)預熱(re)(re)(re)器(qi)，利用抽汽(qi)(qi)預熱(re)(re)(re)來(lai)自除氧(yang)器(qi)的(de)給(gei)(gei)(gei)水(shui)，加(jia)熱(re)(re)(re)給(gei)(gei)(gei)水(shui)溫(wen)度到260℃，再(zai)依(yi)(yi)次進入各(ge)級熔(rong)(rong)(rong)(rong)(rong)鹽(yan)(yan)(yan)汽(qi)(qi)水(shui)換熱(re)(re)(re)器(qi)(如圖9所示)。

熔(rong)鹽(yan)(yan)(yan)汽(qi)水預(yu)熱器采(cai)用(yong)管殼式換熱器，由(you)于水側(ce)壓(ya)(ya)力(li)高，走(zou)(zou)管側(ce)，鹽(yan)(yan)(yan)側(ce)壓(ya)(ya)力(li)低，走(zou)(zou)殼側(ce)。考(kao)慮換熱器需要適應(ying)快速(su)(su)變負荷工(gong)況(kuang)，壓(ya)(ya)力(li)、溫度及流(liu)(liu)量變化較(jiao)大(da)，采(cai)用(yong)U形(xing)管結構(gou)，可(ke)有(you)(you)效吸收因(yin)熱膨脹產生的軸向位移，適應(ying)快速(su)(su)變負荷工(gong)況(kuang)。換熱管采(cai)用(yong)45°布管方式，有(you)(you)效減緩振動。鑒于三(san)元鹽(yan)(yan)(yan)蒸汽(qi)發(fa)生器系統(tong)的熔(rong)鹽(yan)(yan)(yan)側(ce)流(liu)(liu)量較(jiao)大(da)，約是二(er)(er)元鹽(yan)(yan)(yan)系統(tong)的2倍。因(yin)此(ci)，三(san)元鹽(yan)(yan)(yan)蒸汽(qi)發(fa)生系統(tong)采(cai)用(yong)G型分流(liu)(liu)殼體型式，有(you)(you)效降低殼側(ce)壓(ya)(ya)損，而(er)二(er)(er)元鹽(yan)(yan)(yan)選擇(ze)E型殼體型式，二(er)(er)元鹽(yan)(yan)(yan)和(he)(he)三(san)元鹽(yan)(yan)(yan)汽(qi)水預(yu)熱器選型分別為BEU和(he)(he)BGU，如(ru)圖9-10所示。

熔(rong)鹽(yan)(yan)汽(qi)(qi)(qi)(qi)(qi)水(shui)(shui)蒸(zheng)(zheng)發(fa)(fa)(fa)(fa)器(qi)(qi)(qi)的汽(qi)(qi)(qi)(qi)(qi)水(shui)(shui)側將飽(bao)和(he)(he)水(shui)(shui)加(jia)熱(re)(re)(re)(re)成(cheng)飽(bao)和(he)(he)蒸(zheng)(zheng)汽(qi)(qi)(qi)(qi)(qi)，其中(zhong)給水(shui)(shui)來(lai)自熔(rong)鹽(yan)(yan)汽(qi)(qi)(qi)(qi)(qi)水(shui)(shui)預熱(re)(re)(re)(re)器(qi)(qi)(qi)，熔(rong)鹽(yan)(yan)來(lai)自熔(rong)鹽(yan)(yan)汽(qi)(qi)(qi)(qi)(qi)水(shui)(shui)過熱(re)(re)(re)(re)器(qi)(qi)(qi)。熔(rong)鹽(yan)(yan)汽(qi)(qi)(qi)(qi)(qi)水(shui)(shui)蒸(zheng)(zheng)發(fa)(fa)(fa)(fa)器(qi)(qi)(qi)在(zai)整(zheng)個(ge)熔(rong)鹽(yan)(yan)蒸(zheng)(zheng)汽(qi)(qi)(qi)(qi)(qi)發(fa)(fa)(fa)(fa)生系統(tong)中(zhong)，熱(re)(re)(re)(re)負荷占比最(zui)(zui)高(gao)，換熱(re)(re)(re)(re)面積大(da)(da)，設(she)備體(ti)積龐大(da)(da)，且汽(qi)(qi)(qi)(qi)(qi)水(shui)(shui)側發(fa)(fa)(fa)(fa)生相變，內(nei)(nei)部存在(zai)汽(qi)(qi)(qi)(qi)(qi)水(shui)(shui)混合物(wu)兩(liang)相流(liu)體(ti)，流(liu)動與傳熱(re)(re)(re)(re)機理(li)較(jiao)為復(fu)雜，設(she)計難度(du)最(zui)(zui)大(da)(da)。根據汽(qi)(qi)(qi)(qi)(qi)水(shui)(shui)所(suo)在(zai)的位置(zhi)不(bu)(bu)同、原理(li)不(bu)(bu)同，熔(rong)鹽(yan)(yan)汽(qi)(qi)(qi)(qi)(qi)水(shui)(shui)蒸(zheng)(zheng)發(fa)(fa)(fa)(fa)器(qi)(qi)(qi)常見的為換熱(re)(re)(re)(re)管(guan)管(guan)外沸騰(teng)與管(guan)內(nei)(nei)沸騰(teng)兩(liang)種。其中(zhong)管(guan)外沸騰(teng)以釜式(shi)蒸(zheng)(zheng)發(fa)(fa)(fa)(fa)器(qi)(qi)(qi)最(zui)(zui)為常見，在(zai)化工(gong)和(he)(he)光熱(re)(re)(re)(re)領域得到了廣泛應(ying)用。但受加(jia)工(gong)制造技術(shu)的限制，釜式(shi)蒸(zheng)(zheng)發(fa)(fa)(fa)(fa)器(qi)(qi)(qi)的熱(re)(re)(re)(re)功率受限。此外，由于(yu)(yu)熔(rong)鹽(yan)(yan)進口(kou)(kou)溫度(du)與出口(kou)(kou)溫度(du)溫差(cha)較(jiao)大(da)(da)，在(zai)管(guan)板的上下及兩(liang)側均(jun)存在(zai)較(jiao)大(da)(da)熱(re)(re)(re)(re)應(ying)力。管(guan)內(nei)(nei)蒸(zheng)(zheng)發(fa)(fa)(fa)(fa)的汽(qi)(qi)(qi)(qi)(qi)包式(shi)蒸(zheng)(zheng)發(fa)(fa)(fa)(fa)器(qi)(qi)(qi)相較(jiao)于(yu)(yu)釜式(shi)蒸(zheng)(zheng)發(fa)(fa)(fa)(fa)器(qi)(qi)(qi)，具有更高(gao)熱(re)(re)(re)(re)負荷。且蒸(zheng)(zheng)發(fa)(fa)(fa)(fa)器(qi)(qi)(qi)管(guan)側入口(kou)(kou)過冷水(shui)(shui)溫度(du)接近飽(bao)和(he)(he)溫度(du)，出口(kou)(kou)為汽(qi)(qi)(qi)(qi)(qi)水(shui)(shui)混合物(wu)，溫度(du)為飽(bao)和(he)(he)溫度(du)，溫差(cha)極(ji)小，能夠有效改善管(guan)側進出口(kou)(kou)溫差(cha)熱(re)(re)(re)(re)應(ying)力。綜(zong)上所(suo)述，熔(rong)鹽(yan)(yan)汽(qi)(qi)(qi)(qi)(qi)水(shui)(shui)蒸(zheng)(zheng)發(fa)(fa)(fa)(fa)器(qi)(qi)(qi)的選型為BEU式(shi)汽(qi)(qi)(qi)(qi)(qi)包式(shi)蒸(zheng)(zheng)發(fa)(fa)(fa)(fa)器(qi)(qi)(qi)(如圖9-10)。

熔鹽(yan)汽(qi)水(shui)過(guo)熱(re)(re)(re)(re)器(qi)對(dui)應汽(qi)水(shui)側(ce)將飽和蒸(zheng)汽(qi)加(jia)熱(re)(re)(re)(re)至過(guo)熱(re)(re)(re)(re)蒸(zheng)汽(qi)，其中飽和蒸(zheng)汽(qi)來自(zi)熔鹽(yan)汽(qi)水(shui)蒸(zheng)發(fa)器(qi)，熔鹽(yan)來自(zi)熱(re)(re)(re)(re)鹽(yan)罐。熔鹽(yan)汽(qi)水(shui)過(guo)熱(re)(re)(re)(re)器(qi)采(cai)用(yong)管(guan)(guan)殼式(shi)(shi)換(huan)熱(re)(re)(re)(re)器(qi)，蒸(zheng)汽(qi)壓(ya)(ya)力(li)高走管(guan)(guan)側(ce)，熔鹽(yan)壓(ya)(ya)力(li)低走殼側(ce)。由于進口(kou)與(yu)出口(kou)溫差較大(da)，且(qie)溫度(du)(du)較高，換(huan)熱(re)(re)(re)(re)器(qi)又(you)經常運行在(zai)快速變(bian)負荷工況，壓(ya)(ya)力(li)、溫度(du)(du)及流量變(bian)化較大(da)，因(yin)此換(huan)熱(re)(re)(re)(re)器(qi)型(xing)式(shi)(shi)采(cai)用(yong)發(fa)夾式(shi)(shi)(HAP)，如圖(tu)9-10所(suo)示。采(cai)用(yong)該類(lei)型(xing)換(huan)熱(re)(re)(re)(re)器(qi)一方面(mian)避(bi)免(mian)了管(guan)(guan)板(ban)受到(dao)大(da)溫差應力(li)的(de)作(zuo)用(yong)，另一方面(mian)換(huan)熱(re)(re)(re)(re)管(guan)(guan)與(yu)殼體可有效(xiao)吸收因(yin)熱(re)(re)(re)(re)膨脹產生(sheng)的(de)軸向位(wei)移(yi)，避(bi)免(mian)因(yin)熱(re)(re)(re)(re)應力(li)而發(fa)生(sheng)破壞，影(ying)響換(huan)熱(re)(re)(re)(re)器(qi)安(an)全運行。

根據前(qian)文確定(ding)的(de)邊界條件，采用HTRI軟件進行換(huan)熱(re)(re)(re)(re)器(qi)熱(re)(re)(re)(re)力計(ji)算及(ji)設(she)計(ji)。在設(she)計(ji)工(gong)況下，二元鹽(yan)蒸(zheng)汽發生(sheng)系(xi)統(tong)需要增(zeng)設(she)熔鹽(yan)給(gei)水預(yu)熱(re)(re)(re)(re)器(qi)(如(ru)圖10)，即(ji)從(cong)原(yuan)機組抽取合適(shi)參數的(de)蒸(zheng)汽送入給(gei)水預(yu)熱(re)(re)(re)(re)器(qi)加(jia)熱(re)(re)(re)(re)器(qi)來(lai)自除氧器(qi)的(de)給(gei)水。給(gei)水預(yu)熱(re)(re)(re)(re)器(qi)的(de)蒸(zheng)汽側入口溫(wen)度為393.8℃，壓(ya)(ya)力為6.94 MPa，出口溫(wen)度為284.2℃，壓(ya)(ya)力為6.83 MPa；水側入口水溫(wen)為198.5℃，出口水溫(wen)為260℃，熱(re)(re)(re)(re)負荷(he)16.9 MW。給(gei)水預(yu)熱(re)(re)(re)(re)器(qi)分為兩級，均為管(guan)(guan)殼式換(huan)熱(re)(re)(re)(re)器(qi)(BFU和BEU型)，采用U形管(guan)(guan)結構，可有效吸收因(yin)熱(re)(re)(re)(re)膨脹產(chan)生(sheng)的(de)軸向位移，避免熱(re)(re)(re)(re)應力引起(qi)的(de)破壞，影響換(huan)熱(re)(re)(re)(re)器(qi)安全運行。此外，設(she)計(ji)工(gong)況下，熔鹽(yan)蒸(zheng)汽發生(sheng)系(xi)統(tong)三級換(huan)熱(re)(re)(re)(re)器(qi)的(de)參數如(ru)表2所示。

綜上(shang)所述，二(er)元(yuan)鹽與三元(yuan)鹽蒸汽(qi)發生(sheng)系統的(de)主(zhu)要(yao)區別(bie)包(bao)括(kuo)：

1)設計工況(kuang)下，除(chu)氧器給(gei)水(shui)溫度為198.5℃，低(di)于(yu)二元鹽(yan)熔(rong)點，高于(yu)三(san)元鹽(yan)熔(rong)鹽(yan)熔(rong)點，三(san)元鹽(yan)蒸(zheng)汽發(fa)生系統(tong)無需設置(zhi)給(gei)水(shui)預熱器，系統(tong)流(liu)程更簡潔。

2)二元鹽(yan)(yan)(yan)比(bi)三元鹽(yan)(yan)(yan)使用(yong)溫度(du)高(gao)(gao)(gao)，產生(sheng)的(de)(de)(de)蒸(zheng)汽(qi)品位更(geng)(geng)高(gao)(gao)(gao)。因(yin)此，二元鹽(yan)(yan)(yan)蒸(zheng)汽(qi)發(fa)(fa)生(sheng)系(xi)統(tong)產生(sheng)的(de)(de)(de)蒸(zheng)汽(qi)匯入汽(qi)輪機(ji)的(de)(de)(de)位置更(geng)(geng)靠前，具有更(geng)(geng)高(gao)(gao)(gao)的(de)(de)(de)發(fa)(fa)電效率，對應蒸(zheng)汽(qi)發(fa)(fa)生(sheng)系(xi)統(tong)熱功率小(xiao)，換熱器的(de)(de)(de)尺寸和單(dan)次升負(fu)荷過程的(de)(de)(de)用(yong)鹽(yan)(yan)(yan)量均(jun)比(bi)三元鹽(yan)(yan)(yan)蒸(zheng)汽(qi)發(fa)(fa)生(sheng)系(xi)統(tong)少。

4.4熔鹽蒸汽發生系統投資對比

本(ben)文研(yan)究的(de)(de)(de)(de)(de)耦合燃(ran)(ran)煤發(fa)(fa)(fa)(fa)電(dian)(dian)(dian)機組的(de)(de)(de)(de)(de)熔鹽(yan)蒸(zheng)汽發(fa)(fa)(fa)(fa)生系(xi)(xi)統(tong)為燃(ran)(ran)煤機組提供3%Pe/min的(de)(de)(de)(de)(de)升(sheng)負荷(he)速(su)率，使燃(ran)(ran)煤機組的(de)(de)(de)(de)(de)升(sheng)負荷(he)速(su)率達到6%Pe/min，瞄(miao)準(zhun)的(de)(de)(de)(de)(de)是未來(lai)電(dian)(dian)(dian)網(wang)的(de)(de)(de)(de)(de)需求，遠高于(yu)現有機組的(de)(de)(de)(de)(de)升(sheng)負荷(he)速(su)率，無法根據現行的(de)(de)(de)(de)(de)標(biao)準(zhun)進行收益計算。另外(wai)(wai)，耦合燃(ran)(ran)煤發(fa)(fa)(fa)(fa)電(dian)(dian)(dian)的(de)(de)(de)(de)(de)熔鹽(yan)系(xi)(xi)統(tong)目前處于(yu)研(yan)發(fa)(fa)(fa)(fa)和初步建設階段，在役期間將間斷(duan)運行，缺乏(fa)年利用(yong)(yong)小時數、廠用(yong)(yong)電(dian)(dian)(dian)率、運行維護(hu)成(cheng)本(ben)、繳納稅額等全壽命周期數據，難以(yi)進行常規平準(zhun)化發(fa)(fa)(fa)(fa)電(dian)(dian)(dian)成(cheng)本(ben)(LCOE)計算。因此本(ben)文借鑒國內外(wai)(wai)權威機構關于(yu)光(guang)熱電(dian)(dian)(dian)站熔鹽(yan)蒸(zheng)汽發(fa)(fa)(fa)(fa)生系(xi)(xi)統(tong)設備投資計算公(gong)式(shi)及(ji)廠家調(diao)研(yan)，僅以(yi)熔鹽(yan)蒸(zheng)汽發(fa)(fa)(fa)(fa)生系(xi)(xi)統(tong)的(de)(de)(de)(de)(de)投資成(cheng)本(ben)作為比較二元鹽(yan)和三元鹽(yan)熔鹽(yan)蒸(zheng)汽發(fa)(fa)(fa)(fa)生系(xi)(xi)統(tong)經(jing)濟(ji)性的(de)(de)(de)(de)(de)評判標(biao)準(zhun)。

熔(rong)(rong)鹽(yan)蒸(zheng)汽發生(sheng)系(xi)統(tong)設備(bei)(bei)是主要(yao)(yao)(yao)投資(zi)組成，主要(yao)(yao)(yao)包括各級(ji)換熱器、熔(rong)(rong)鹽(yan)儲罐、動力設備(bei)(bei)和管道等。此外(wai)，熔(rong)(rong)鹽(yan)用量在熔(rong)(rong)鹽(yan)蒸(zheng)汽發生(sheng)系(xi)統(tong)投資(zi)成本中占比較大，需要(yao)(yao)(yao)在系(xi)統(tong)的經濟性分析(xi)中考慮(lv)。

具體的(de)說(shuo)，熔(rong)鹽汽(qi)水(shui)換(huan)熱器(qi)的(de)投(tou)資成本(ben)是傳熱面積、結構型式、所選材料和壓力(li)的(de)函數。根據文獻[46,47]，當換(huan)熱器(qi)面積2時，換(huan)熱器(qi)的(de)投(tou)資成本(ben)計算(suan)如下：

根據熔鹽汽水換熱器的面積、運行壓力(li)等參(can)數，結(jie)合式(shi)(6)-(9)，最終(zhong)確定二元(yuan)(yuan)鹽蒸(zheng)汽發生(sheng)系(xi)(xi)統投(tou)資(zi)(zi)成本(ben)為499.5萬(wan)元(yuan)(yuan)，三元(yuan)(yuan)鹽蒸(zheng)汽發生(sheng)系(xi)(xi)統投(tou)資(zi)(zi)成本(ben)為682.5萬(wan)元(yuan)(yuan)，比二元(yuan)(yuan)鹽系(xi)(xi)統高183.0萬(wan)元(yuan)(yuan)。

熔(rong)(rong)鹽(yan)(yan)(yan)(yan)罐為(wei)(wei)(wei)(wei)圓柱形立罐式結構(gou)，尺寸由溫度差和儲熱(re)(re)介(jie)質的(de)(de)等壓熱(re)(re)容決定。根據熔(rong)(rong)鹽(yan)(yan)(yan)(yan)運行溫度區間，二元(yuan)(yuan)(yuan)鹽(yan)(yan)(yan)(yan)蒸(zheng)(zheng)(zheng)汽(qi)(qi)發(fa)生(sheng)系統(tong)熱(re)(re)鹽(yan)(yan)(yan)(yan)罐工(gong)(gong)(gong)作溫度為(wei)(wei)(wei)(wei)550℃，選(xuan)材(cai)為(wei)(wei)(wei)(wei)TP347H，冷鹽(yan)(yan)(yan)(yan)罐的(de)(de)工(gong)(gong)(gong)作溫度為(wei)(wei)(wei)(wei)310℃，選(xuan)材(cai)為(wei)(wei)(wei)(wei)Q345，三元(yuan)(yuan)(yuan)鹽(yan)(yan)(yan)(yan)蒸(zheng)(zheng)(zheng)汽(qi)(qi)發(fa)生(sheng)系統(tong)冷熱(re)(re)鹽(yan)(yan)(yan)(yan)罐的(de)(de)工(gong)(gong)(gong)作溫度分(fen)(fen)別(bie)(bie)(bie)為(wei)(wei)(wei)(wei)235℃和390℃，選(xuan)材(cai)均(jun)為(wei)(wei)(wei)(wei)Q345。根據設計工(gong)(gong)(gong)況下熔(rong)(rong)鹽(yan)(yan)(yan)(yan)蒸(zheng)(zheng)(zheng)汽(qi)(qi)發(fa)生(sheng)系統(tong)熱(re)(re)力計算結果(guo)，得(de)到二元(yuan)(yuan)(yuan)鹽(yan)(yan)(yan)(yan)和三元(yuan)(yuan)(yuan)蒸(zheng)(zheng)(zheng)汽(qi)(qi)發(fa)生(sheng)系統(tong)峰值升負荷(he)(he)功率分(fen)(fen)別(bie)(bie)(bie)為(wei)(wei)(wei)(wei)136.5 MW和165.8 MW(如圖9-10)，熔(rong)(rong)鹽(yan)(yan)(yan)(yan)系統(tong)支撐升負荷(he)(he)時長為(wei)(wei)(wei)(wei)500 s，由此確(que)定二元(yuan)(yuan)(yuan)鹽(yan)(yan)(yan)(yan)和三元(yuan)(yuan)(yuan)鹽(yan)(yan)(yan)(yan)蒸(zheng)(zheng)(zheng)汽(qi)(qi)發(fa)生(sheng)系統(tong)單次升負荷(he)(he)過程所需熱(re)(re)量分(fen)(fen)別(bie)(bie)(bie)為(wei)(wei)(wei)(wei)9.5 MWhth和11.5 MWhth。以滿足10次3%Pe/min的(de)(de)升負荷(he)(he)需求為(wei)(wei)(wei)(wei)目標，考慮熔(rong)(rong)鹽(yan)(yan)(yan)(yan)罐底(di)部、設備和管道中不(bu)能有效利用的(de)(de)熔(rong)(rong)鹽(yan)(yan)(yan)(yan)量，最終(zhong)確(que)定二元(yuan)(yuan)(yuan)鹽(yan)(yan)(yan)(yan)和三元(yuan)(yuan)(yuan)鹽(yan)(yan)(yan)(yan)的(de)(de)用量分(fen)(fen)別(bie)(bie)(bie)為(wei)(wei)(wei)(wei)1700 t和2500 t，儲熱(re)(re)量分(fen)(fen)別(bie)(bie)(bie)為(wei)(wei)(wei)(wei)95.0 MWhth和115.0 MWhth。

熔鹽儲罐(guan)及(ji)相關配件計算公(gong)式如(ru)下：

式(10)中(zhong)，WT為(wei)熔鹽罐(guan)的(de)儲熱(re)量，D1為(wei)熱(re)鹽罐(guan)的(de)材(cai)(cai)料(liao)(liao)成(cheng)(cheng)(cheng)本(ben)(ben)(ben)(ben)與(yu)(yu)(yu)安裝、建(jian)設(she)成(cheng)(cheng)(cheng)本(ben)(ben)(ben)(ben)之和，為(wei)46元/kWhth，D2為(wei)冷鹽罐(guan)的(de)材(cai)(cai)料(liao)(liao)成(cheng)(cheng)(cheng)本(ben)(ben)(ben)(ben)與(yu)(yu)(yu)安裝、建(jian)設(she)成(cheng)(cheng)(cheng)本(ben)(ben)(ben)(ben)之和，為(wei)21元/kWhth，D3為(wei)罐(guan)體保(bao)溫材(cai)(cai)料(liao)(liao)成(cheng)(cheng)(cheng)本(ben)(ben)(ben)(ben)與(yu)(yu)(yu)安裝、建(jian)設(she)成(cheng)(cheng)(cheng)本(ben)(ben)(ben)(ben)之和，為(wei)5元/kWhth，D4為(wei)地(di)基(ji)、支(zhi)撐(cheng)結(jie)構的(de)材(cai)(cai)料(liao)(liao)成(cheng)(cheng)(cheng)本(ben)(ben)(ben)(ben)與(yu)(yu)(yu)安裝、建(jian)設(she)成(cheng)(cheng)(cheng)本(ben)(ben)(ben)(ben)之和，為(wei)17元/kWhth，D5為(wei)電(dian)氣儀(yi)表的(de)材(cai)(cai)料(liao)(liao)成(cheng)(cheng)(cheng)本(ben)(ben)(ben)(ben)與(yu)(yu)(yu)安裝、建(jian)設(she)成(cheng)(cheng)(cheng)本(ben)(ben)(ben)(ben)之和，為(wei)6元/kWhth，D6為(wei)管道(dao)、閥(fa)門(men)及其它配件的(de)材(cai)(cai)料(liao)(liao)成(cheng)(cheng)(cheng)本(ben)(ben)(ben)(ben)與(yu)(yu)(yu)安裝、建(jian)設(she)成(cheng)(cheng)(cheng)本(ben)(ben)(ben)(ben)之和，為(wei)2元/kWhth。

本(ben)文按照式(shi)(10)對熔鹽(yan)罐及其附屬設備(bei)的投(tou)資(zi)成本(ben)進行計算，得(de)到(dao)二元鹽(yan)蒸汽發生系(xi)統(tong)(tong)熔鹽(yan)儲罐的投(tou)資(zi)成本(ben)約921.5萬(wan)元，三元鹽(yan)蒸汽發生系(xi)統(tong)(tong)熔鹽(yan)儲罐的建的投(tou)資(zi)成本(ben)約1115.5萬(wan)元，比二元鹽(yan)系(xi)統(tong)(tong)高194.0萬(wan)元。

表1中給出了調研得到的(de)二(er)元(yuan)鹽(yan)和(he)三元(yuan)鹽(yan)的(de)市場價格區間，取平均值對(dui)應二(er)元(yuan)鹽(yan)和(he)三元(yuan)鹽(yan)的(de)價格分別為(wei)7000元(yuan)/t和(he)7500元(yuan)/t。根據(ju)熔鹽(yan)的(de)用量，最終(zhong)確定(ding)二(er)元(yuan)鹽(yan)蒸(zheng)汽發(fa)生系(xi)統熔鹽(yan)成(cheng)本為(wei)1190.0萬(wan)元(yuan)，二(er)元(yuan)鹽(yan)蒸(zheng)汽發(fa)生系(xi)統熔鹽(yan)成(cheng)本為(wei)1875.0萬(wan)元(yuan)，比二(er)元(yuan)鹽(yan)系(xi)統高685萬(wan)元(yuan)。

熔(rong)鹽(yan)(yan)蒸(zheng)(zheng)(zheng)汽(qi)(qi)(qi)發(fa)(fa)(fa)生(sheng)(sheng)(sheng)(sheng)(sheng)系(xi)統(tong)(tong)(tong)涉(she)及的(de)(de)動力(li)設(she)備(bei)主(zhu)要(yao)包括熱(re)(re)鹽(yan)(yan)泵(beng)(beng)和(he)(he)給(gei)(gei)水(shui)泵(beng)(beng)，其(qi)中熱(re)(re)鹽(yan)(yan)泵(beng)(beng)布置在熱(re)(re)鹽(yan)(yan)罐出口(kou)，主(zhu)要(yao)用于給(gei)(gei)熔(rong)鹽(yan)(yan)汽(qi)(qi)(qi)水(shui)換熱(re)(re)器(qi)輸送熱(re)(re)鹽(yan)(yan)，給(gei)(gei)水(shui)泵(beng)(beng)用于將除氧器(qi)的(de)(de)給(gei)(gei)水(shui)泵(beng)(beng)送至(zhi)熔(rong)鹽(yan)(yan)蒸(zheng)(zheng)(zheng)汽(qi)(qi)(qi)發(fa)(fa)(fa)生(sheng)(sheng)(sheng)(sheng)(sheng)系(xi)統(tong)(tong)(tong)。泵(beng)(beng)的(de)(de)流(liu)量(liang)、工質、壓(ya)力(li)等是影(ying)響熱(re)(re)鹽(yan)(yan)泵(beng)(beng)和(he)(he)給(gei)(gei)水(shui)泵(beng)(beng)造(zao)價(jia)的(de)(de)主(zhu)要(yao)因素。參(can)考(kao)由(you)SNL、DOE和(he)(he)NREL共同完(wan)成的(de)(de)技(ji)術(shu)路(lu)線報告(gao)，熱(re)(re)鹽(yan)(yan)泵(beng)(beng)的(de)(de)造(zao)價(jia)將隨(sui)著(zhu)系(xi)統(tong)(tong)(tong)存(cun)儲能量(liang)容量(liang)的(de)(de)增加(jia)(jia)而增加(jia)(jia)，熱(re)(re)熔(rong)鹽(yan)(yan)泵(beng)(beng)的(de)(de)價(jia)格為(wei)(wei)40元(yuan)(yuan)(yuan)/kWth，二(er)(er)(er)元(yuan)(yuan)(yuan)鹽(yan)(yan)和(he)(he)三元(yuan)(yuan)(yuan)鹽(yan)(yan)蒸(zheng)(zheng)(zheng)汽(qi)(qi)(qi)發(fa)(fa)(fa)生(sheng)(sheng)(sheng)(sheng)(sheng)系(xi)統(tong)(tong)(tong)輸出的(de)(de)最大功率分(fen)別為(wei)(wei)136.5 MWth和(he)(he)165.8 MWth，因此二(er)(er)(er)元(yuan)(yuan)(yuan)鹽(yan)(yan)和(he)(he)三元(yuan)(yuan)(yuan)鹽(yan)(yan)蒸(zheng)(zheng)(zheng)汽(qi)(qi)(qi)發(fa)(fa)(fa)生(sheng)(sheng)(sheng)(sheng)(sheng)系(xi)統(tong)(tong)(tong)熱(re)(re)鹽(yan)(yan)泵(beng)(beng)的(de)(de)成本分(fen)別為(wei)(wei)546.0萬(wan)(wan)(wan)元(yuan)(yuan)(yuan)和(he)(he)663.2萬(wan)(wan)(wan)元(yuan)(yuan)(yuan)，比二(er)(er)(er)元(yuan)(yuan)(yuan)鹽(yan)(yan)系(xi)統(tong)(tong)(tong)高117.2萬(wan)(wan)(wan)元(yuan)(yuan)(yuan)。熔(rong)鹽(yan)(yan)系(xi)統(tong)(tong)(tong)給(gei)(gei)水(shui)泵(beng)(beng)為(wei)(wei)較(jiao)為(wei)(wei)成熟的(de)(de)常規設(she)備(bei)，經市場調研得(de)到(dao)二(er)(er)(er)元(yuan)(yuan)(yuan)鹽(yan)(yan)和(he)(he)三元(yuan)(yuan)(yuan)鹽(yan)(yan)蒸(zheng)(zheng)(zheng)汽(qi)(qi)(qi)發(fa)(fa)(fa)生(sheng)(sheng)(sheng)(sheng)(sheng)系(xi)統(tong)(tong)(tong)給(gei)(gei)水(shui)泵(beng)(beng)的(de)(de)價(jia)位分(fen)別為(wei)(wei)150萬(wan)(wan)(wan)元(yuan)(yuan)(yuan)和(he)(he)100萬(wan)(wan)(wan)元(yuan)(yuan)(yuan)。綜上所(suo)述，二(er)(er)(er)元(yuan)(yuan)(yuan)鹽(yan)(yan)蒸(zheng)(zheng)(zheng)汽(qi)(qi)(qi)發(fa)(fa)(fa)生(sheng)(sheng)(sheng)(sheng)(sheng)系(xi)統(tong)(tong)(tong)動力(li)設(she)備(bei)投(tou)資為(wei)(wei)696.0萬(wan)(wan)(wan)元(yuan)(yuan)(yuan)，二(er)(er)(er)元(yuan)(yuan)(yuan)鹽(yan)(yan)蒸(zheng)(zheng)(zheng)汽(qi)(qi)(qi)發(fa)(fa)(fa)生(sheng)(sheng)(sheng)(sheng)(sheng)系(xi)統(tong)(tong)(tong)動力(li)設(she)備(bei)投(tou)資為(wei)(wei)763.2萬(wan)(wan)(wan)元(yuan)(yuan)(yuan)，比二(er)(er)(er)元(yuan)(yuan)(yuan)鹽(yan)(yan)系(xi)統(tong)(tong)(tong)高67.2萬(wan)(wan)(wan)元(yuan)(yuan)(yuan)。根(gen)據管(guan)(guan)(guan)道的(de)(de)流(liu)量(liang)、系(xi)統(tong)(tong)(tong)阻力(li)考(kao)慮不同介質的(de)(de)流(liu)速，液體流(liu)速2~4 m/s，蒸(zheng)(zheng)(zheng)汽(qi)(qi)(qi)10~20 m/s，計(ji)算(suan)(suan)不同管(guan)(guan)(guan)道的(de)(de)管(guan)(guan)(guan)徑，再根(gen)據設(she)計(ji)條件選(xuan)取(qu)(qu)(qu)管(guan)(guan)(guan)道的(de)(de)材質、計(ji)算(suan)(suan)管(guan)(guan)(guan)道壁厚。二(er)(er)(er)元(yuan)(yuan)(yuan)鹽(yan)(yan)蒸(zheng)(zheng)(zheng)汽(qi)(qi)(qi)發(fa)(fa)(fa)生(sheng)(sheng)(sheng)(sheng)(sheng)系(xi)統(tong)(tong)(tong)設(she)計(ji)溫(wen)(wen)度>400℃的(de)(de)管(guan)(guan)(guan)道材質選(xuan)取(qu)(qu)(qu)TP347H不銹(xiu)鋼(gang)，主(zhu)蒸(zheng)(zheng)(zheng)汽(qi)(qi)(qi)管(guan)(guan)(guan)道選(xuan)取(qu)(qu)(qu)12Cr1MoVG，其(qi)余管(guan)(guan)(guan)道為(wei)(wei)20G，三元(yuan)(yuan)(yuan)鹽(yan)(yan)蒸(zheng)(zheng)(zheng)汽(qi)(qi)(qi)發(fa)(fa)(fa)生(sheng)(sheng)(sheng)(sheng)(sheng)系(xi)統(tong)(tong)(tong)所(suo)有(you)管(guan)(guan)(guan)道設(she)計(ji)溫(wen)(wen)度均，管(guan)(guan)(guan)道材質選(xuan)取(qu)(qu)(qu)20G。核(he)算(suan)(suan)得(de)到(dao)二(er)(er)(er)元(yuan)(yuan)(yuan)鹽(yan)(yan)比三元(yuan)(yuan)(yuan)鹽(yan)(yan)蒸(zheng)(zheng)(zheng)汽(qi)(qi)(qi)發(fa)(fa)(fa)生(sheng)(sheng)(sheng)(sheng)(sheng)系(xi)統(tong)(tong)(tong)管(guan)(guan)(guan)道投(tou)資成本增加(jia)(jia)~131萬(wan)(wan)(wan)元(yuan)(yuan)(yuan)，詳見表3。

綜合考慮(lv)熔(rong)鹽(yan)蒸汽(qi)(qi)(qi)發(fa)(fa)(fa)(fa)(fa)生(sheng)(sheng)(sheng)系(xi)統(tong)(tong)(tong)(tong)(tong)熔(rong)鹽(yan)側和(he)汽(qi)(qi)(qi)水側運行(xing)溫度、介質(zhi)流量(liang)/流速、換(huan)熱(re)(re)(re)器(qi)熱(re)(re)(re)負荷(he)、系(xi)統(tong)(tong)(tong)(tong)(tong)壓(ya)力(li)及支撐升負荷(he)次數(shu)等邊界條件，進行(xing)換(huan)熱(re)(re)(re)器(qi)、熔(rong)鹽(yan)儲罐、熔(rong)鹽(yan)用量(liang)、動力(li)設(she)備和(he)管(guan)道尺寸、材質(zhi)的(de)(de)設(she)計計算。二(er)元(yuan)鹽(yan)和(he)三元(yuan)鹽(yan)蒸汽(qi)(qi)(qi)發(fa)(fa)(fa)(fa)(fa)生(sheng)(sheng)(sheng)系(xi)統(tong)(tong)(tong)(tong)(tong)換(huan)熱(re)(re)(re)器(qi)面(mian)積(ji)和(he)主(zhu)要投資(zi)對比如(ru)圖11所示(shi)，受限于不(bu)同(tong)種(zhong)類(lei)熔(rong)鹽(yan)運行(xing)溫度、熔(rong)鹽(yan)系(xi)統(tong)(tong)(tong)(tong)(tong)發(fa)(fa)(fa)(fa)(fa)電(dian)效率(lv)等，相同(tong)發(fa)(fa)(fa)(fa)(fa)電(dian)量(liang)對應二(er)元(yuan)鹽(yan)蒸汽(qi)(qi)(qi)發(fa)(fa)(fa)(fa)(fa)生(sheng)(sheng)(sheng)系(xi)統(tong)(tong)(tong)(tong)(tong)的(de)(de)熱(re)(re)(re)負荷(he)低，換(huan)熱(re)(re)(re)器(qi)面(mian)積(ji)為2090.6 m2，僅(jin)為三元(yuan)鹽(yan)蒸汽(qi)(qi)(qi)發(fa)(fa)(fa)(fa)(fa)生(sheng)(sheng)(sheng)系(xi)統(tong)(tong)(tong)(tong)(tong)換(huan)熱(re)(re)(re)器(qi)面(mian)積(ji)的(de)(de)~0.38倍(bei)(如(ru)圖11a)，三元(yuan)鹽(yan)蒸汽(qi)(qi)(qi)發(fa)(fa)(fa)(fa)(fa)生(sheng)(sheng)(sheng)系(xi)統(tong)(tong)(tong)(tong)(tong)換(huan)熱(re)(re)(re)器(qi)的(de)(de)投資(zi)成本高于二(er)元(yuan)鹽(yan)。此(ci)外，二(er)元(yuan)鹽(yan)蒸汽(qi)(qi)(qi)發(fa)(fa)(fa)(fa)(fa)生(sheng)(sheng)(sheng)系(xi)統(tong)(tong)(tong)(tong)(tong)管(guan)道投資(zi)大(da)于三元(yuan)鹽(yan)蒸汽(qi)(qi)(qi)發(fa)(fa)(fa)(fa)(fa)生(sheng)(sheng)(sheng)系(xi)統(tong)(tong)(tong)(tong)(tong)，三元(yuan)鹽(yan)蒸汽(qi)(qi)(qi)發(fa)(fa)(fa)(fa)(fa)生(sheng)(sheng)(sheng)系(xi)統(tong)(tong)(tong)(tong)(tong)熔(rong)鹽(yan)投資(zi)約為二(er)元(yuan)鹽(yan)的(de)(de)1.5倍(bei)，熔(rong)鹽(yan)儲罐的(de)(de)投資(zi)成本約是二(er)元(yuan)鹽(yan)的(de)(de)1.2倍(bei)，動力(li)設(she)備的(de)(de)投資(zi)成本基(ji)本一致(如(ru)圖11b)。

綜上分析，二(er)(er)元(yuan)鹽(yan)蒸(zheng)汽發生(sheng)系(xi)統主要投(tou)資成(cheng)本~3526.8萬元(yuan)，三元(yuan)鹽(yan)蒸(zheng)汽發生(sheng)系(xi)統主要投(tou)資成(cheng)本~4525.1萬元(yuan)，比二(er)(er)元(yuan)鹽(yan)蒸(zheng)汽發生(sheng)系(xi)統高~1000萬元(yuan)。

五、結論

本文(wen)以(yi)350 MW靈(ling)活燃煤發電(dian)機(ji)組為研(yan)究對象，提出可獨立承擔3%Pe/min升負(fu)荷速率的熔(rong)鹽(yan)系統(tong)。綜合系統(tong)熱力計算(suan)與設(she)備(bei)傳(chuan)熱分析(xi)，對二元鹽(yan)和三元鹽(yan)蒸汽(qi)發生系統(tong)發電(dian)效(xiao)率、系統(tong)復雜性及(ji)投資成本進(jin)行對比(bi)研(yan)究，主要結論如下：

(1)相比于三元(yuan)(yuan)鹽(yan)，二元(yuan)(yuan)鹽(yan)分(fen)解溫(wen)度高，能產(chan)生較高品位蒸汽(qi)，發(fa)電(dian)效(xiao)率更高。設(she)計工況下三元(yuan)(yuan)鹽(yan)蒸汽(qi)發(fa)生系統發(fa)電(dian)效(xiao)率為29.2%，二元(yuan)(yuan)鹽(yan)蒸汽(qi)發(fa)生系統發(fa)電(dian)效(xiao)率達到36.7%，提高了7.5個百分(fen)點。

(2)相比于三元(yuan)鹽(yan)(yan)(yan)，二(er)元(yuan)鹽(yan)(yan)(yan)熔點高，來(lai)自除氧器的(de)給水需經過兩級抽(chou)汽預(yu)熱，防(fang)止(zhi)熔鹽(yan)(yan)(yan)在預(yu)熱器中凝固(gu)堵塞，因此二(er)元(yuan)鹽(yan)(yan)(yan)蒸汽發生系統略復雜。

(3)相比(bi)于三元(yuan)鹽，二元(yuan)鹽運行溫度高，設(she)備(bei)和管(guan)道需(xu)要(yao)更貴的鋼材。然而，滿(man)足相同升負(fu)(fu)荷需(xu)求下，二元(yuan)鹽用量少，相應熔鹽儲罐體積(ji)降低(di)；其次，二元(yuan)鹽蒸汽(qi)發生(sheng)(sheng)系(xi)統熱(re)負(fu)(fu)荷小，換熱(re)器(qi)面積(ji)減小。綜合(he)考慮上述因素二元(yuan)鹽蒸汽(qi)發生(sheng)(sheng)系(xi)統投資成本更低(di)。

(4)為構(gou)建支撐(cheng)靈活燃煤發電的高效(xiao)、安全(quan)熔鹽系統，綜合(he)以上(shang)技術(shu)經濟(ji)性分析，本文建議在(zai)實際(ji)工(gong)程中采用(yong)二元鹽。